Tag Archives: vaccination

When do we stop vaccinating against an infectious disease?

The Conversation

File 20170529 25219 1v9l85i
In Australia we still vaccinate against polio, but not tuberculosis. Why, and how do we decide? From http://www.shutterstock.com.au

Rebecca Chisholm, University of Melbourne and Nicholas Geard, University of Melbourne

Australia was declared measles-free in 2014. However, the recent importation of a case of measles into Australia from Indonesia illustrates the threat this disease still poses to Australians. It also underscores the importance of maintaining high vaccination rates against rare diseases to ensure re-introductions don’t lead to outbreaks.

But when will we be at a point where it’s safe to stop vaccinating against measles? Or against other rare and infectious diseases?

In short, vaccinating against an infectious disease can stop once the threat of future transmission is deemed sufficiently low. This may occur as a consequence of a disease being eliminated or eradicated.

Disease elimination

An infectious disease is considered to be eliminated from a geographical region if the number of new cases observed over some period of time in that region drops to zero. But the ease of global travel can result in previously eliminated diseases being re-introduced.

Recent outbreaks of measles in Australia highlight how imported cases can lead to serious outbreaks in regions declared to be disease-free.

High levels of population immunity from good vaccine coverage can protect against outbreaks following disease re-introductions. For example, polio is considered eliminated in Australia (since 2000).

However, in 2007 wild poliovirus was isolated from a man in Australia who had recently arrived from a foreign country. On this occasion, good vaccine coverage and consequent population immunity prevented the imported virus from spreading in the community.

Disease eradication

If a disease has been eliminated globally it is said to be eradicated. There is then no risk of re-introduction to a disease-free region.

The eradication of an infectious disease is much harder to achieve than elimination. This is mainly due to the global level of coordination required. Only one human disease has been successfully eradicated. Smallpox was declared eradicated in 1979 following a lengthy but coordinated global effort.

Smallpox had many characteristics that made it suitable for targeted eradication. For example, it had obvious symptoms that allowed easy identification of cases, while a short incubation period reduced its ability to spread undetected. An effective vaccine also existed for smallpox, which further aided eradication efforts.

Elimination and eradication are both more challenging for some diseases than others. For example, eliminating diseases that can infect other species, such as malaria, or survive in the wider environment, such as cholera, is more difficult. Diseases that evolve rapidly, such as influenza, are also likely to be with us for some time.

Stopping routine vaccination

The safest point to stop vaccinating against a disease is obviously after it has been eradicated globally. In practice, routine vaccination programs are ended before this. When the risk of infection is deemed low enough, the human and economic costs of routine vaccination may outweigh the benefits, leading to the decision to discontinue the program.

All vaccines have an economic cost to produce and deliver, and some may also have side effects. For example, smallpox vaccination, while safe for most people, occasionally caused more serious reactions.

However, as smallpox was such a dire disease, this cost was deemed acceptable in countries with high disease prevalence where the risk of infection was substantial. In countries in which smallpox was eliminated, this cost was no longer justifiable. Instead, routine vaccination was ended before eradication because the risk of harm from the vaccine exceeded the risk of harm from the disease.

Similarly, routine vaccination against tuberculosis (TB) is not considered necessary in low-prevalence countries. In Australia, routine vaccination against TB ceased in the mid-1980s. While serious complications from the TB vaccine are rare (less than one in a million doses, the majority of which are self-limiting), the vaccine is only about 50% effective in preventing TB disease.

The main benefit of the vaccine is that it significantly reduces the risk of serious illness from TB, particularly in children. Hence, in countries like Australia where TB is rare, the overall benefits of routine vaccination are minimal because it is not expected to significantly reduce the number of infectious cases. Instead the TB vaccine is targeted toward high-risk groups, such as the close contacts of people with TB.

Future eradication efforts

Malaria and wild poliovirus are two well-known pathogens currently targeted for eradication by the World Health Organisation. Wild poliovirus is nearing the final stages of eradication, the so-called endgame of the disease. It has been eliminated in all but two countries (Afghanistan and Pakistan).

A number of challenges emerge during the endgame of a disease. Infection is circulating at low levels and possibly only in hard-to-reach groups. This can make case detection and targeted control efforts difficult.

Communities in which circulation of a disease has been greatly reduced can also become disengaged from eradication efforts, leading to disease resurgence. Political and social factors, such as weak health systems, conflict and population displacement, can amplify the effects of non-compliance with eradication efforts.

Measles is another disease for which global eradication is deemed technically possible. Despite elimination in some countries, including Australia, targets for measles elimination in Europe have not been met in recent years.

The ConversationUntil global eradication of highly transmissible diseases such as measles and polio is achieved, routine vaccination programs will remain an effective means of protecting populations from the risk of outbreaks that can result from imported cases.

Rebecca Chisholm, Research Fellow, Melbourne School of Population and Global Health, University of Melbourne and Nicholas Geard, ARC DECRA Research Fellow, Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne

This article was originally published on The Conversation. (Reblogged by permission). Read the original article.

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Please don’t do your own research on immunisation; you’ll get it wrong

The Conversation

Michael Vagg, Deakin University

Pauline Hanson has become the latest politician to flirt with the fringe view of immunisation denial. Of course, like all thoroughly modern anti-vaxxers, she claims to be about choice and empowerment rather than denial of the overwhelming scientific consensus. The Conversation

Of all the weasel words immunisation deniers use, I get most infuriated by the “do your own research” trope.

You don’t need to. Unless you’re a senior research scientist with your own lab, a posse of postdocs and serious wad of cash, we don’t need your help.

What Senator Hanson appears to mean is that she wants average people who find misinformation on the internet to be allowed to disagree with decades of rigorous, serious scientific effort. Unlike so many of my medical colleagues, I make an effort to keep up with goings-on in the anti-vax movement so I am grimly aware of the depths of hubris and folly that inform the “research” you so easily find when you innocently Google for vaccine information. The average person with high-school science knowledge and healthy faith in human decency has no chance.

Someone who has limited time and attention would not possibly bother to wade through the byzantine details of how Andrew Wakefield’s fraud was uncovered and the scurrilous ongoing attempts to smear Brian Deer, the investigative journalist who brought it to light.

Only a dogged student of human nature would have the stomach to watch videos featuring the pseudoscientific ramblings of the supposed intellectual leaders of this wretched movement. Yet many of us have done this for you. Trust me, there is no wisdom or learning in these cranks.

Only the real enthusiasts would have watched with bemusement last month as the Chiropractors’ Association of Australia (CAA) had a public spat on their own Facebook page with the AV-sN, Australia’s leading anti-vax organisation. CAA finally got around to demanding the removal of a link from AV-sN website endorsing their chiropractic philosophy of opposing immunisation. Their public statement read in part:

It has come to our attention that the Australian Vaccination-sceptics Network contains a link to the CAA National website. We have requested that they remove this link to our website as a matter of urgency.

The Chiropractors’ Association of Australia (CAA) does not support the views promoted by the Australian Vaccination-sceptics Network.

The former president of the anti-vaxxers then further embarrassed CAA by turning up in the comment section and lamenting:

More and more chiropractors are speaking out against their governing body trying to tell them that they must ignore basic chiropractic philosophy of the power that made the body heals the body in order to gain acceptance from mainstream medicine. When will the CAA understand that mainstream medicine’s only concern is to maintain their own authoritarian monopoly and destroy any and all competitors?

I’ve previously documented how CAA has been providing anti-vax speakers at official learning activities approved for professional development by their regulator, but you won’t find this information on the front page of your Google search. As recently as 2015, the CAA National Conference featured several speakers with links to the antivax movement. But again, the background briefing needed to appreciate the importance of this is not available to any but the most hardcore anti-vax-watchers.

I could go on and on in this vein, but I’ll spare you. Suffice to say that everywhere you get suspicion and hostility about immunisation you also get shoddy thinking and misrepresentation of plain facts. You get routine denial of reality and genuinely unhinged discourse. Science becomes The Enemy. Ideology trumps evidence.

There is no worthwhile political debate to be had here. Giving such deformed pseudoscience any media oxygen at all is reckless. It is unworthy of a serious aspirant to political power. By parroting the coded messages of the anti-vax movement, and encouraging hesitant parents to “do their own research” Senator Hanson is enabling an unspeakable industry to thrive. Make no mistake, there are hucksters both big and small raking in money by manufacturing hostility towards one of the greatest gifts our benighted species has managed to give itself.

All these cretins want is the chance to get unwary, perhaps vulnerable parents in front of their finely tuned propaganda.

What Senator Hanson has just done is give them a flood of fresh eyeballs to sell to.

Michael Vagg, Clinical Senior Lecturer at Deakin University School of Medicine & Pain Specialist, Deakin University

This article was originally published on The Conversation. (Reblogged by permission).  Read the original article.

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The Fallacy of Faulty Risk Assessment

by Tim Harding

(An edited version of this essay was published in The Skeptic magazine, September 2016, Vol 36 No 3)

Australian Skeptics have tackled many false beliefs over the years, often in co-operation with other organisations.  We have had some successes – for instance, belief in homeopathy finally seems to be on the wane.  Nevertheless, false beliefs about vaccination and fluoridation just won’t lie down and die – despite concerted campaigns by medical practitioners, dentists, governments and more recently the media.  Why are these beliefs so immune to evidence and arguments?

There are several possible explanations for the persistence of these false beliefs.  One is denialism – the rejection of established facts in favour of personal opinions.  Closely related are conspiracy theories, which typically allege that facts have been suppressed or fabricated by ‘the powers that be’, in an attempt by denialists to explain the discrepancies between their opinions and the findings of science.  A third possibility is an error of reasoning or fallacy known as Faulty Risk Assessment, which is the topic of this article.

Before going on to discuss vaccination and fluoridation in terms of this fallacy, I would like to talk about risk and risk assessment in general.

What is risk assessment?

Hardly anything we do in life is risk-free. Whenever we travel in a car or even walk along a footpath, most people are aware that there is a small but finite risk of being injured or killed.  Yet this risk does not keep us away from roads.  We intuitively make an informal risk assessment that the level of this risk is acceptable in the circumstances.

In more formal terms, ‘risk’ may be defined as the probability or likelihood of something bad happening multiplied by the resulting cost/benefit ratio if it does happen.  Risk analysis is the process of discovering what risks are associated with a particular hazard, including the mechanisms that cause the hazard, then estimating the likelihood that the hazard will occur and the consequences if it does occur.

Risk assessment is the determination of the acceptability of risk using two dimensions of measurement – the likelihood of an adverse event occurring; and the severity of the consequences if it does occur, as illustrated in the diagram below.  (This two-dimensional risk assessment is a conceptually useful way of ranking risks, even if one or both of the dimensions cannot be measured quantitatively).

risk-diagram

By way of illustration, the likelihood of something bad happening could be very low, but the consequences could be unacceptably high – enough to justify preventative action.  Conversely, the likelihood of an event could be higher, but the consequences could low enough to justify ‘taking the risk’.

In assessing the consequences, consideration needs to be given to the size of the population likely to be affected, and the severity of the impact on those affected.  This will provide an indication of the aggregate effect of an adverse event.  For example, ‘high’ consequences might include significant harm to a small group of affected individuals, or moderate harm to a large number of individuals.

A fallacy is committed when a person either focuses on the risks of an activity and ignores its benefits; and/or takes account one dimension of risk assessment and overlooks the other dimension.

To give a practical example of a one-dimensional risk assessment, the desalination plant to augment Melbourne’s water supply has been called a ‘white elephant’ by some people, because it has not been needed since the last drought broke in March 2010.  But this criticism ignores the catastrophic consequences that could have occurred had the drought not broken.  In June 2009, Melbourne’s water storages fell to 25.5% of capacity, the lowest level since the huge Thomson Dam began filling in 1984.  This downward trend could have continued at that time, and could well be repeated during the inevitable next drought.

wonthaggi

Melbourne’s desalination plant at Wonthaggi

No responsible government could afford to ‘take the risk’ of a major city of more than four million people running out of water.  People in temperate climates can survive without electricity or gas, but are likely to die of thirst in less than a week without water, not to mention the hygiene crisis that would occur without washing or toilet flushing.  The failure to safeguard the water supply of a major city is one of the most serious derelictions of government responsibility imaginable.

Turning now to the anti-vaccination and anti-fluoridation movements, they both commit the fallacy of Faulty Risk Assessment.  They focus on the very tiny likelihood of adverse side effects without considering the major benefits to public health from vaccination and the fluoridation of public water supplies, and the potentially severe consequences of not vaccinating or fluoridating.

Vaccination risks

The benefits of vaccination far outweigh its risks for all of the diseases where vaccines are available.  This includes influenza, pertussis (whooping cough), measles and tetanus – not to mention the terrible diseases that vaccination has eradicated from Australia such as smallpox, polio, diphtheria and tuberculosis.

As fellow skeptic Dr. Rachael Dunlop puts it:  ‘In many ways, vaccines are a victim of their own success, leading us to forget just how debilitating preventable diseases can be – not seeing kids in calipers or hospital wards full of iron lungs means we forget just how serious these diseases can be.’

No adult or teenager has ever died or become seriously ill in Australia from the side effects of vaccination; yet large numbers of people have died from the lack of vaccination.  The notorious Wakefield allegation in 1998 of a link between vaccination and autism has been discredited, retracted and found to be fraudulent.  Further evidence comes from a recently published exhaustive review examining 12,000 research articles covering eight different vaccines which also concluded there is no link between vaccines and autism.

According to Professor C Raina MacIntyre of UNSW, ‘Influenza virus is a serious infection, which causes 1,500 to 3,500 deaths in Australia each year.  Death occurs from direct viral effects (such as viral pneumonia) or from complications such as bacterial pneumonia and other secondary bacterial infections. In people with underlying coronary artery disease, influenza may also precipitate heart attacks, which flu vaccine may prevent.’

In 2010, increased rates of high fever and febrile convulsions were reported in children under 5 years of age after they were vaccinated with the Fluvax vaccine.  This vaccine has not been registered for use in this age group since late 2010 and therefore should not be given to children under 5 years of age. The available data indicate that there is a very low risk of fever, which is usually mild and transient, following vaccination with the other vaccine brands.  Any of these other vaccines can be used in children aged 6 months and older.

Australia was declared measles-free in 2005 by the World Health Organization (WHO) – before we stopped being so vigilant about vaccinating and outbreaks began to reappear.  The impact of vaccine complacency can be observed in the 2015 measles epidemic in Wales where there were over 800 cases and one death, and many people presenting were of the age who missed out on MMR vaccination following the Wakefield scare.

After the link to autism was disproven, many anti-vaxers shifted the blame to thiomersal, a mercury-containing component of relatively low toxicity to humans.  Small amounts of thiomersal were used as a preservative in some vaccines, but not the MMR vaccine.  Thiomersal was removed from all scheduled childhood vaccines in 2000.

In terms of risk assessment, Dr. Dunlop has pointed out that no vaccine is 100% effective and vaccines are not an absolute guarantee against infection. So while it’s still possible to get the disease you’ve been vaccinated against, disease severity and duration will be reduced.  Those who are vaccinated have fewer complications than people who aren’t.  With pertussis (whooping cough), for example, severe complications such as pneumonia and encephalitis (brain inflammation) occur almost exclusively in the unvaccinated.  So since the majority of the population is vaccinated, it follows that most people who get a particular disease will be vaccinated, but critically, they will suffer fewer complications and long-term effects than those who are completely unprotected.

Fluoridation risks

Public water fluoridation is the adjustment of the natural levels of fluoride in drinking water to a level that helps protect teeth against decay.  In many (but not all) parts of Australia, reticulated drinking water has been fluoridated since the early 1960s.

The benefits of fluoridation are well documented.  In November 2007, the NHMRC completed a review of the latest scientific evidence in relation to fluoride and health.  Based on this review, the NHMRC recommended community water fluoridation programs as the most effective and socially equitable community measure for protecting the population from tooth decay.  The scientific and medical support for the benefits of fluoridation certainly outweighs the claims of the vocal minority against it.

Fluoridation opponents over the years have claimed that putting fluoride in water causes health problems, is too expensive and is a form of mass medication.  Some conspiracy theorists go as far as to suggest that fluoridation is a communist plot to lower children’s IQ.  Yet, there is no evidence of any adverse health effects from the fluoridation of water at the recommended levels.  The only possible risk is from over-dosing water supplies as a result of automated equipment failure, but there is inline testing of fluoride levels with automated water shutoffs in the remote event of overdosing.  Any overdose would need to be massive to have any adverse effect on health.  The probability of such a massive overdose is extremely low.

Tooth decay remains a significant problem. In Victoria, for instance, more than 4,400 children under 10, including 197 two-year-olds and 828 four-year-olds, required general anaesthetic in hospital for the treatment of dental decay during 2009-10.  Indeed, 95% of all preventable dental admissions to hospital for children up to nine years old in Victoria are due to dental decay. Children under ten in non-optimally fluoridated areas are twice as likely to require a general anaesthetic for treatment of dental decay as children in optimally fluoridated areas.

As fellow skeptic and pain management specialist Dr. Michael Vagg has said, “The risks of general anaesthesia for multiple tooth extractions are not to be idly contemplated for children, and far outweigh the virtually non-existent risk from fluoridation.”  So in terms of risk assessment, the risks from not fluoridating water supplies are far greater than the risks of fluoridating.

Implications for skeptical activism

Anti-vaxers and anti-fluoridationists who are motivated by denialism and conspiracy theories tend to believe whatever they want to believe, and dogmatically so.  Thus evidence and arguments are unlikely to have much influence on them.

But not all anti-vaxxers and anti-fluoridationists fall into this category.  Some may have been misled by false information, and thus could possibly be open to persuasion if the correct information is provided.

Others might even be aware of the correct information, but are assessing the risks fallaciously in the ways I have described in this article.  Their errors are not ones of fact, but errors of reasoning.  They too might be open to persuasion if education about sound risk assessment is provided.

I hope that analysing the false beliefs about vaccination and fluoridation from the perspective of the Faulty Risk Assessment Fallacy has provided yet another weapon in the skeptical armoury against these false beliefs.

References

Rachael Dunlop (2015) Six myths about vaccination – and why they’re wrong. The Conversation, Parkville.

C Raina MacIntyre (2016) Thinking about getting the 2016 flu vaccine? Here’s what you need to know. The Conversation, Parkville.

Mike Morgan (2012) How fluoride in water helps prevent tooth decay.  The Conversation, Parkville.

Michael Vagg (2013) Fluoride conspiracies + activism = harm to children. The Conversation, Parkville.

 Government of Victoria (2014) Victorian Guide to Regulation. Department of Treasury and Finance, Melbourne.

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‘No Vax, No Visit’? If mum was vaccinated baby is already protected against whooping cough

The Conversation

Samantha Carlson, University of Sydney; Kerrie Wiley, University of Sydney, and Peter Bruce McIntyre, University of Sydney

NO VAX, NO VISIT! Our baby girl is due in four weeks. We can’t wait to meet her! If you would like to meet her, we ask that you ask your doctor for a whooping cough booster this week. Our daughter can’t receive her first vaccination until she’s six weeks old, so relies on us to keep her safe from germs. #NoVaxNoVisit

Have you seen these requests in your social media feeds recently?

No Vax, No Visit is a movement being propagated through social media and social pressure. Expectant parents are demanding that all visitors who wish to visit their newborn are recently vaccinated against whooping cough. If visitors can’t prove they’re vaccinated, they’re refused permission to visit the baby in hospital or at home until after the newborn’s two-month vaccination (which can be given at six weeks).

It is understandable that prospective parents, aware of how devastating whooping cough can be, want to leave no stone unturned to protect their baby. But is it supported by the best evidence?

No Vax, No Visit is an unofficial extension of the “cocooning” strategy, recommended by the Australian Immunisation Handbook since 2003.

The official cocooning recommendation is to vaccinate regular household contacts if they haven’t had a whooping cough booster within the last ten years. This strategy targets parents, siblings, grandparents and anyone who is in regular contact with babies, as they are the most common sources of infection in newborns.

‘Cocooning’ doesn’t mean a baby can’t come into contact with anyone who hasn’t been vaccinated. Tom Leuntjens/Flickr, CC BY

The cocooning recommendation doesn’t mean that anyone who comes through the front door to visit and say a quick hello must be vaccinated. It doesn’t mean regular household contacts need to be vaccinated for every child born within those ten years.

Although the idea of creating a “cocoon” of protection around babies is attractive, this approach has limitations. And eliminating all possible sources of whooping cough this way just isn’t possible.

So, what should parents do?

Evidence became available in 2014 that showed if mums are vaccinated during pregnancy, the vaccine is 91% effective in preventing severe whooping cough in very young infants.

When a mum is vaccinated during pregnancy, the protective antibodies travel across the placenta and into the baby. It’s essentially a baby’s first vaccine, so the baby is born with an army of antibodies ready for defence.

Contrary to the American vaccine insert, many studies, such as this one, have actually tested the vaccine on tens of thousands of pregnant women. The studies demonstrate how effective and safe this is for pregnant mums and their unborn child. Subsequently, in March 2015, the Australian Immunisation Handbook began recommending that women who are between 28 and 32 weeks pregnant receive a whooping cough booster for each pregnancy.

If mums follow this pregnancy recommendation, the vaccination of all visitors (in addition to regular household contacts) could theoretically offer a small amount of additional protection for the baby. However, there’s no evidence to say this is the case. The person more likely to benefit is the one receiving the vaccination, particularly if they are elderly.

Social consequences

Important things to consider with No Vax, No Visit are the unintended social consequences.

While some parents will find their family and friends are happy to be vaccinated, we are also hearing stories of isolation of new parents, division in social groups, and guilt of friends feeling irresponsible. Some new parents are even too scared to take their baby to the “disease-riddled” shopping centre, school or playground.

What seems to be forgotten is the high level of protection the baby already has if mum was vaccinated while pregnant.

While there’s no evidence that No Vax, No Visit will offer any additional protection for the newborn, there is evidence that social isolation can lead to postnatal depression. This is particularly important when we consider one in seven new mothers in Australia experiences postnatal depression.

Support for new parents is most needed during the newborn’s first few weeks of life. If new parents don’t have any visitors and are too scared to go out into the world with their newborn, what effect will this have on the family’s wellbeing?

So, what else can parents do to protect their newborn before the six-week vaccination if mum was vaccinated during pregnancy, and dad, siblings and grandparents are all up to date with their vaccines? Ask visitors to postpone their visit if they are sick, and hand-washing before cuddles is essential.

With all this in place, there’s little or no extra benefit from No Vax, No Visit.

The ConversationSamantha Carlson, Social Science Research Officer for the National Centre for Immunisation Research and Surveillance, University of Sydney; Kerrie Wiley, Research Fellow, National Centre for Immunisation Research & Surveillance, and School of Public Health, University of Sydney, and Peter Bruce McIntyre, Professor and Director for the National Centre for Immunisation Research and Surveillance of Vaccine, University of Sydney

This article was originally published on The Conversation. (Reblogged by permission). Read the original article.

 

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Thinking about getting the 2016 flu vaccine? Here’s what you need to know

The Conversation

C Raina MacIntyre, UNSW Australia and Aye Moa, UNSW Australia

Up to one in ten adults and three in ten children are infected with influenza each year.

The vaccine we have used for decades, the trivalent vaccine (TIV), protects against three strains of flu. But in 2016, for the first time, the publicly funded vaccine program will offer the quadrivalent flu vaccine (QIV), which protects against four instead of three strains of flu.

The seasonal influenza vaccination is now available at GP clinics and pharmacies. For those not eligible for the free vaccine, it will cost around A$9$15 for the TIV and A$12$25 for the QIV, plus the cost of the consultation if your GP doesn’t bulk bill.

So, what strains do these vaccines protect against? Who should be vaccinated? And, if you’re paying, what additional benefit does the new QIV have?

What is influenza?

Influenza virus is a serious infection, which causes 1,500 to 3,500 deaths in Australia each year. Death occurs from direct viral effects (such as viral pneumonia) or from complications such as bacterial pneumonia and other secondary bacterial infections.

In people with underlying coronary artery disease, influenza may also precipitate heart attacks, which flu vaccine may prevent.

The two major types of influenza infection are influenza A and B; the A strain causes more severe disease than B. Influenza B, however, may be under-reported and causes more severe illness in children and young adults.

The Influenza A virus has much greater genetic diversity than B, probably because it has several non-human animal hosts such as birds, pigs and horses. This sets the scene for genetic mixing between human and animal strains, which accounts for the diversity of the virus, along with constant changes each year as it tries to evade its hosts’ immune responses.

The flu vax may also protect against heart attacks in those with underlying disease. Government of Alberta/Flickr, CC BY-NC-ND

Minor changes (drift) account for new viruses circulating each season, whereas major changes (shift) result in new pandemic strains, to which humans have little or no pre-existing immunity. Influenza B, in contrast, has only two major lineages and much less genetic diversity; seals are the only animal host.

Pandemic strains of the past, once established in human populations, become seasonal strains and tend to cycle over the years, with different strains dominating each year.

Seasonal vaccination

The influenza vaccine is formulated annually because seasonal flu viruses undergo continuous genetic mutation and the vaccine needs to match the major circulating strains. A vaccine from a previous year will generally not confer much protection the following year.

The holy grail of influenza vaccines is a universal vaccine, a one-off shot that would give lifelong protection. Such vaccines are being developed and may not be far off.

Until that time, every year The World Health Organisation studies the circulating viruses and decides which strains will be covered in that year’s flu vaccine. This process occurs separately for the southern and northern hemispheres. It’s usually successful, but a mismatch between the circulating flu virus and the vaccine may sometimes occur.

While live flu vaccines are available in other countries, only the inactivated vaccine is available in Australia. This cannot cause influenza, as it does not contain live virus.

The trivalent vaccine (TIV) contains protection against three strains: two of influenza A and one of influenza B. But there are two major circulating lineages of influenza B, and recent research shows that a TIV B vaccine mismatch occurs approximately 25% of the time.

The quadrivalent (QIV) strain protects against the second B lineage.

Different flu strains dominate each year. Claus Rebler/Flickr, CC BY-SA

Several different companies manufacture TIV and QIV. The vaccines are safe and effective, although one brand, Fluvax, is not approved for children under the age of five years because of an increased risk of febrile seizures.

The 2016 Australian trivalent inactivated influenza vaccine protects against:

  • A (H1N1): an A/California/7/2009 (H1N1)-like virus
  • A (H3N2): an A/Hong Kong/4801/2014 (H3N2)-like virus (H3N2 is generally the most severe form of influenza A)
  • B: a B/Brisbane/60/2008-like virus.

The quadrivalent inactivated influenza vaccine (QIV) protects against the three strains about and an additional B lineage:

  • B/Phuket/3073/2013-like virus.

Should I get vaccinated?

Australia’s national immunisation program recommends and funds free flu vaccinations for:

  • people aged 65 years and older
  • Aboriginal and Torres Strait Islander people aged 15 years or older
  • pregnant women
  • anyone over six months of age with a medical condition such as heart disease, respiratory disease, diabetes, kidney disease, asthma, immunosuppression and chronic neurological conditions
  • children on long-term aspirin therapy.

Pneumonia is a common complication of influenza, so people with risk factors are also recommended for pneumococcal vaccine.

Those at risk of complications from the flu are eligible for the free vaccine. Direct Relief/Flickr, CC BY-NC-ND

About 70% of people over 65 are vaccinated, but only 30-50% of people aged under 65 years with risk factors get vaccinated each year.

Australians who don’t fall within one of these at-risk groups may choose to get vaccinated to protect themselves, family members, colleagues/patients or friends.

The 2016 flu season

Flu seasons typically cycle between mild and severe epidemic years.

The 2015 Australian flu season was dominated by two lineages of influenza B (62% of cases), the highest influenza B season since 2008. Children five to nine years old, adults aged 35 to 44 and the elderly aged over 85 were most affected.

The major influenza A viruses in circulation last year were influenza A (H1N1) pdm09 and, to a lesser degree, influenza A (H3N2).

The effectiveness of the flu vaccine varies each year. Both TIV and QIV can protect well if the circulating strains are similar to the vaccine strains.

In the United States, the Centers for Disease Control and Prevention (CDC) reported that vaccine effectiveness for the 2015-2016 flu season was about 60%, and the vaccine strains a good match for the season.

Any person recommended for vaccination on the National Immunisation Program schedule should get vaccinated as early as possible. They will be able to benefit from the QIV, which confers greater protection by eliminating the possibility of B lineage mismatch.

But if paying for the vaccine privately and cost is an issue, the TIV is more affordable and will still confer good protection.


Further reading: Health Check: when is ‘the flu’ really a cold?

The ConversationC Raina MacIntyre, Professor of Infectious Diseases Epidemiology, Head of the School of Public Health and Community Medicine, UNSW Australia and Aye Moa, PhD candidate, UNSW Australia

This article was originally published on The Conversation. (Reblogged by permission). Read the original article.

 

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Are vaccines making viruses more dangerous?

The Conversation

Dave Hawkes, University of Melbourne

Despite the near-universal acceptance of the benefits of vaccination, some people still worry about risks associated with their use. Luckily, scientists are vigilant about identifying possible risks, so they can be addressed before problems emerge.

Still, people sometimes forget that science is the process by which we arrive at solutions. And they worry about incremental scientific steps that often expose weakness in these solutions.

A recent study published in the journal PLOS Biology, for instance, was presented by some media as claiming that certain vaccines make viruses more dangerous. The research showed chickens treated with its vaccine are more likely to spread a highly virulent strain of Marek’s disease virus, a condition that affects poultry.

The reason was simple: the vaccine used in the study targets Marek’s disease, not the virus that causes it. These types of vaccines are known as “leaky vaccines” because they don’t affect the ability of the virus to reproduce and spread to others; they simply prevent the virus from causing disease.

Marek’s disease vaccines use a non-disease-causing virus to infect cells. This preventive infection stops tumour formation and death when those cells are infected by the Marek’s disease virus.

But the virus can replicate and still produce more virus particle, which can infect other chickens. All Marek’s disease vaccines, since their introduction in the 1970s, have been leaky; they allow chickens to carry and spread the virus without getting the disease.

‘Imperfect-vaccine hypothesis’

The effect of leaky vaccines on how disease spreads is explained by the “imperfect-vaccine hypothesis”. It holds that, without vaccination, a very virulent virus can get into a population and kill infected hosts (people or animals) very quickly – before they have a chance to spread it. This means that the virus will die out very quickly too, as all potential hosts will be dead or immune to it.

A leaky vaccine can prevent the very virulent virus from killing the host, but doesn’t stop that host from spreading the virus to others. This means that a very virulent virus can survive for long periods in the vaccinated hosts. And it can continue to spread in this time, making it less likely to die out.

The PLOS Biology study showed chickens vaccinated against Marek’s disease were more likely to spread the disease to other chickens, than unvaccinated chickens were. The unvaccinated chickens all died in less than ten days – before they could spread the virus.

The vaccinated chickens, on the other hand, were protected from the disease so were able to spread the virus to other (unvaccinated) chickens for weeks and weeks. And they made those chickens immune to the virus in the process.

Marek’s disease, which affects poultry, has a ‘leaky’ vaccine’. David Goehring/Flickr, CC BY-SA

One of the reasons the researchers looked at Marek’s disease in chickens is because it has been getting progressively deadlier. Originally, the disease occurred mainly in older chickens and caused paralysis. But an acute form of the disease emerged in the 1950s and has since become the dominant form. This rather virulent version can kill up to 100% of unvaccinated birds.

Leaky but not sinking

But what does all this mean for the future of vaccination?

Well, the first thing to note is that in this study the vaccinated chickens always had the best outcome. In one experiment, only three out of 50 unvaccinated chickens survived the disease, while vaccination protected the majority of chickens (46 out of 50 survived).

The authors also noted that vaccination has been very effective in preventing deaths in chickens due to Marek’s disease. They said their study didn’t indicate whether vaccination played any role in the development of the serious form of Marek’s disease.

Vaccines prevent disease, even if they’re leaky. But it’s important to note there are currently no vaccines against viruses that infect humans that are leaky. Current human vaccines mimic the body’s own response to viruses.

But yet-to-be-developed vaccines for diseases such as HIV, Ebola or malaria, where humans have been unable to mount an effective natural defence, are likely to be leaky. And even imperfect vaccines for these illnesses would be an enormous step forward.

The possible effect of “leaky vaccines” on how viruses spread is an interesting new observation. But there are a number of other ways by which viruses can change in response to vaccination.

An arms race

One response of viruses to vaccines involves the evolution of viral proteins that allow them to escape the vaccine. This is known as “epitope evolution” and it’s the reason flu vaccines change each year.

Even if a vaccine is effective in preventing a particular strain of virus, other strains may take its place. This was a concern when the human papillomavirus (HPV) vaccine was introduced nearly ten years ago. But researchers have investigated whether any HPV types not in the vaccine have become more common since the vaccine was introduced and there’s no evidence this is happening.

The interaction between viruses and their targets can change over time. In the case of Marek’s disease, the infection has become progressively deadlier. Increased use of broiler chickens, lack of genetic diversity in flocks and high-density rearing may all have played a role in the changes seen in the disease.

The benefits of vaccination far outweigh its risks. And it is research like this that helps medical researchers actively identify possible dangers so we can safely continue to avoid the diseases that terrified our parents’ generation.

The ConversationDave Hawkes is Honorary Fellow at Department of Pharmacology and Therapeutics at University of Melbourne

This article was originally published on The Conversation. (Reblogged by permission). Read the original article.
 

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Senator Richard Di Natale on The Australian Vaccination Network

Dr. Richard Di Natale (born 6 June 1970) is an Australian Senator and leader of the parliamentary caucus of the Australian Greens party. Di Natale is a former medical practitioner, and was elected to the Australian Senate in the 2010 Australian federal election.

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In the vaccine debate, science is just getting its boots on

The Conversation

Ian Musgrave

There is an old saying that a lie will be heard around the world while truth is still getting its boots on. This was brought home to me during a radio interview I did on Tuesday night in the wake of the Federal Government’s decision to remove the conscientious objection exemption for vaccination. I was astonished that in 2015, some of these pieces of misinformation are still out there, and still believed, if the passionate radio callers (and several posts in my Facebook feed) are any indication.

Here is a sample of some of the misinformation and misunderstandings I encountered on the radio show and on the internet in the past 24 hours (paraphrased slightly).

“Why should we inject our kids with polyethylene glycol/brake fluid?” We don’t. There is no ethylene glycol in our vaccines. We do have harmless traces of a completely different chemical, 2-phenoxyethanol, which is an antibacterial helping keep the vaccines sterile.

“Why are we injecting our kids with formaldehyde?” Formaldehyde is used to inactivate viruses in some vaccines. After clean-up, minute traces are left, but the amount you would get from a vaccine injection is much less that is circulating naturally in your blood. Yes, your body makes formaldehyde. If you are seriously worried about formaldehyde, don’t eat apples or pears, which contain much more formaldehyde than vaccines. For details see here and here.

“Why are we injecting our kids with mercury?” We aren’t, there has been no mercury in kids vaccines in Australia since 2000. Especially those in the vaccination schedule. Note that the amount of mercury in the Thiomersal preservative is less than what you would get from eating a can of tuna and no one seems to be advocating a fish free diet for kids.

“Why are we still giving kids small pox vaccine when small pox is extinct?” We are not. And I am astonished that anyone would think that we did, but this (paraphrased) was an actual question.

Measles vaccination conquers measles. Source: Epidemiol Rev (2002) 24 (2): 125-136. doi: 10.1093/epirev/mxf002

“But we don’t need vaccines, these diseases were going before vaccines”. Nope, see that graph? That’s the incidence of measles in the UK before and after the vaccine, note the strong correlation between the fall in measles and the vaccine coverage of the population. Similar graphs are seen for the US and Canada (see here for the most dishonest anti-vaccination graph ever).

Australia stopped collecting data on measles incidence so there is a big gap in our data, but the incidence of the disease was higher before the vaccine than after. Same goes for pertussis (we had just had an epidemic when the vaccine was introduced), diptheria and Heamophilus Influenza B (and if you want to claim it’s all hygiene and diet, the HIB vaccine was introduced in the ‘90’s where nutrition and hygiene was at modern standards). See the Australian Academy of Sciences “science of vaccination” for graphs and details.

“There have been no deaths from measles since 2000”, this is actually a false statement about US data. 2000 was the year that endemic measles was declared extinct in the US. In Australia, we haven’t has a measles death since 1995. Unsurprisingly, since vaccination has been so effective.

However, in the US the has been 8 deaths during the epidemics caused by unvaccinated people catching measles overseas and bringing it back to the US, where it spreads mostly amongst the unvaccinated. In the US, it is usually linked to the heinous meme “no measles deaths since 2000, hundreds of measles deaths from the measles vaccine”. This pernicious statement is untrue, there have been no deaths due to the measles vaccine.

“What about that study that showed vaccines cause autism”. No, just no. Andrew Wakefield’s study, since retracted for unethical conduct, was so sloppy that it was meaningless, and may even be fraudulent. This unethical study has caused thousand of people to forgo measles vaccines, with kids getting caught in epidemics that should never have happened.

In the debate about our response to under vaccination, it is assumed that people refusing vaccines are making rational choices, weighing up the pros and cons of vaccination versus side effects with the best available data.

The controversial Leunig cartoon that shows a mother fleeing a barrage of syringes inadvertently sums up what it is really about.

Fear

As the talking points I’ve encountered show, people are coming up with objections that are either wildly distorted or flat out untrue but they all have one thing in common. They all directly stoke the fear that by vaccinating our children we will harm them. A rational choice is difficult to make in this environment.

That a lie can travel around the world before truth gets its boots on is never truer than in this debate. This recent article contains talking points not covered above that are either not true or wildly distorted (Fluarix does not contain foetal bovine serum, the virus for the vaccine is grown in eggs; vaccinations are not intravenous and so on). But I’ve already spent three days and over 1,000 words to cover the standard false or misleading claims and I have to stop at some point.

All the items I talked about have been dealt with long ago. But if you do an internet search for “Australian vaccine information” three of the top five hits are vaccine denialist sites. In this age of Dr. Google sites that play on fears will trump the more sober (and boring) official sites.

My approach to vaccine refusers (the people whose decisions have been influenced by misinformation and fear, as opposed to hard core vaccine denialists) is to provide them with better and more accessible information.

This may not work as well as it might be naively imagined, a study on the best way to provide accurate vaccine information to parents who had previously failed to vaccinate their children found that although the parents understanding of vaccine safety improved, they were no more likely to have their children vaccinated. Some parents became even less likely to vaccinate their children.

Even in the light of this somewhat depressing knowledge, we should not stop trying to get truth out there. One of the difficulties in communicating vaccine facts is that these may leave a gap in peoples beliefs (accounting for their reluctance to accept the facts). An approach I’ve mentioned before is replacing the gap with an alternative narrative. Whichever approach we use, we need to keep the facts front and centre.

Remember, this is not just abstract knowledge, or “cute science facts”, but information that will keep real kids out of hospital and in some case save lives.

Truth (and science) may take time to get its boots on, but those boots were made for walking, and the journey has just begun.

The ConversationThis article was originally published on The Conversation. (Reblogged by permission). Read the original article.


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Immunisation, the media and the amplification of irrational anxiety

The Conversation

Brian McNair, Queensland University of Technology

The government’s ‘no jab, no pay’ policy, which will restrict childcare benefits for those parents who refuse to have their kids immunised, may seem harsh to some. Most parents, however, will see the wisdom of a policy which puts the collective welfare of all children above the conscientious objections of a few parents.

The rate of non-immunisation of children has risen from 1% to 2% in a decade, noted Tony Abbott at a Sunday morning press conference announcing the new policy. 40,000 children are not immunised in Australia, he added, and rates of some very avoidable but potentially lethal children’s diseases such as measles and whooping cough have gone up.

That 2% put at risk the other 98%, and using the tax and benefits system to send that message is tough, but justified.

In the United States and the UK, too, immunisation rates have fallen over recent years, and diseases which once plagued our children, and were then all but wiped out by immunisation programs, have returned in significant numbers. So what has been going on? Why are so many parents refusing to take advantage of a preventive medical technology which has saved literally millions of children’s lives across the world?

One answer, if not the only one – some have deep religious objections, for example – is the news media, and their role in what we might call the amplification of irrational anxiety.

A small but significant minority of parents have come to believe, in all sincerity (and no-one doubts that they have the best interests of their children at heart) that immunisation is dangerous, and certainly riskier than the risks associated with not having their kids vaccinated.

Even though there is no solid evidence to support that belief, and plenty of evidence to support the benefits of immunisation, some parents are so anxious that they will put their own children, and more importantly, other people’s children, at heightened risk of exposure to a preventable disease which could cause disability and even death.

So where have these anxieties come from?

Back in 2004, an English doctor by the name of Andrew Wakefield published research claiming to demonstrate a link between the MMR triple vaccine (to immunise children against mumps, measles and rubella) and the onset of autism. As followers of the story will know, Wakefield’s work was subsequently discredited, and he himself struck off the medical register in the UK for his unethical research methods.

Before that happened, however, the alleged risks of MMR became a major news story in the UK and all over the world. At that time, a decade ago, the global incidence of autism had risen dramatically. Between 1996 and 2007 in the United States, for example, the reported incidence of autism rose from 0.8 per 1,000 to 5.2 – an increase of some 600%.

Similar increases were recorded in many other countries. In Australia, the first survey of the prevalence of autism did not take place until 2006 so historical data are lacking. In 2014, however, the Australian Bureau of Statistics found a 79% increase in diagnoses between 2009 and 2012. A NSW parliament report of 2013 noted that:

… the growing number of children diagnosed with Autism Spectrum Disorder (ASD) is an issue of concern both in Australia and overseas.

This does not mean that the actual prevalence of autism has risen, though. Rather, the public awareness of autism has risen, through movies such as Rain Man and the explosion of media visibility around the condition seen since the 1990s. Documentaries were made about autistic ‘savants’, and families where parents struggled to cope with autistic children. The Curious Incident of the Dog in the Night Time became a global publishing phenomenon, and an entire sub-genre of ‘autism lit’ emerged.

Many people, children and adults, who might hitherto have been described as ‘different’ or ‘eccentric’, or even just ‘shy’, were labelled with Asperger’s Syndrome, or some other condition on the autistic spectrum.

Through a heightened media visibility, parents, medical professionals, teachers and others involved with children were sensitised to a condition which until recently was little known and poorly understood. In other words, autism has always existed, but only recently has it been recognised and given a name. As a result, its recorded incidence has risen dramatically, not because more children are acquiring autism from one cause or another, but because more of those born with it – and autism is often a genetic condition that runs in families and mainly affects males – are being identified.

This is a positive development, because autism is very real, and heightened public awareness has led to support services being put in place for people with autism where there had been none.

Notwithstanding this context, one cannot blame parents for becoming more anxious about the causes of autism, and many quite plausible, if never substantiated, theories have circulated. Wakefield’s research, when it was published in 2004, spoke directly to that anxiety, and his hypothesis – that autism was ‘caused’ by immunisation – seemed credible to many.

In the UK, where the scare was centred, and Wakefield’s work taken very seriously by most of the media, hundreds of thousands of parents withdrew their children from the MMR program. Then-prime minister Tony Blair was asked by journalists to reveal if his baby son Leo had been vaccinated or not. He refused to answer on privacy grounds, while making clear his own absolute confidence in the safety of the vaccine.

Despite such reassurances, and the widespread scepticism which greeted Wakefield’s research amongst his medical peers from the outset, the impact of the scare was very real. Rates of immunisation fell, while the incidence of measles and other preventable diseases began to rise. Ill-founded anxiety about the dangers of immunisation ended up having very real consequences on public health.

Years after Wakefield’s work had been discredited by his peers, his theories on MMR and autism have continued to influence parents all over the world. And where he has had influence, so the incidence of the diseases targeted by the MMR vaccine have risen.

In February this year, the Sunday Times reported on the anti-immunisation advocacy of US group Generation Rescue, who were reported to “seek inspiration” from Wakefield, who now lives and works in that country. The result of this campaign:

… say experts, has been to plunge America into the first national debate since the 1970s about the safety and necessity of vaccines — and led to the return of measles, a highly contagious childhood disease judged extinct by the US government’s Centers for Disease Control (CDC) 15 years ago.

In the US, vaccination rates had fallen by 3%, amid what the article called “a mounting sense of panic”. As in the UK a decade previously, erroneous health information spread through a variety of media channels had provoked a health crisis with strong political reverberations.

Politicians faced with anxious parents were encouraged to comment and pronounce on the vaccination ‘issue’, even when ignorant of the science. Republican contenders for the 2016 presidential race – Chris Christie and Rand Paul – both declared their approval of parental exemptions from MMR vaccination.

Rigorous research into media coverage of autism and its causes has not been done in Australia, and we cannot assume that all of those ‘conscientious objectors’ to immunisation are directly influenced by the Wakefield hypothesis. But his work, and the way it was reported a decade ago and since, undoubtedly contributed to a climate of fear around the risks of vaccination, irrational in so far as it lacks foundation in scientifically validated evidence.

The government is therefore right to take strong action against parents whose irrational fears knowingly put other children at risk. It is an example of firm government in the face of myth and unreason, and should be supported by all who care about the health of our kids.

The ConversationThis article was originally published on The Conversation. (Reblogged by permission). Read the original article.


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Infections of the mind: why anti-vaxxers just ‘know’ they’re right

The Conversation

Thom Scott-Phillips, Durham University

Anti-vaccination beliefs can cause real, substantive harm, as shown by the recent outbreak of measles in the US. These developments are as shocking and distressing as their consequences are predictable. But if the consequences are so predictable, why do the beliefs persist?

It is not simply that anti-vaxxers don’t understand how vaccines work (some of them may not, but not all of them). Neither are anti-vaxxers simply resistant to all of modern medicine (I’m sure that many of them still take pain killers when they need to). So the matter is not as simple as plain stupidity. Some anti-vaxxers are not that stupid, and some stupid people are not anti-vaxxers. There is something more subtle going on.

Naïve theories

We all have what psychologists call “folk” theories, or “naïve” theories, of how the world works. You do not need to learn Newton’s laws to believe that an object will fall to the floor if there is nothing to support it. This is just something you “know” by virtue of being human. It is part of our naïve physics, and it gives us good predictions of what will happen to medium-sized objects on planet earth.

Naïve physics is not such a good guide outside of this environment. Academic physics, which deals with very large and very small objects, and with the universe beyond our own planet, often produces findings that are an affront to common sense.

A life force. Food by Shutterstock

As well as physics, we also have naïve theories about the natural world (naïve biology) and the social world (naïve psychology). An example of naïve biology is “vitalistic causality” – the intuitive belief that a vital power or life force, acquired from food and water, is what makes humans active, prevents them from being taken ill, and enables them to grow. Children have this belief from a very young age.

Naïve theories of all kinds tend to persist even in the face of contradictory arguments and evidence. Interestingly, they persist even in the minds of those who, at a more reflexive level of understanding, know them to be false.

In one study, adults were asked to determine, as quickly as possible, whether a statement was scientifically true or false. These statements were either scientifically true and naïvely true (“A moving bullet loses speed”), scientifically true but naïvely false (“A moving bullet loses height”), scientifically false but naïvely true (“A moving bullet loses force”), or scientifically false and naïvely false (“A moving bullet loses weight”).

Adults with a high degree of science education got the questions right, but were significantly slower to answer when the naïve theory contradicted their scientific understanding. Scientific understanding does not replace naïve theories, it just suppresses them.

Sticky ideas

As ideas spread through a population, some stick and become common, while others do not. The science of how and why ideas spread through populations is called cultural epidemiology. More and more results in this area are showing how naïve theories play a major role in making some ideas stickier than others. Just as we have a natural biological vulnerability to some bacteria and not others, we have a natural psychological vulnerability to some ideas and not others. Some beliefs, good and bad, are just plain infectious.

Here is an example. Bloodletting persisted in the West for centuries, even though it was more often than not harmful to the patient. A recent survey of the ethnographic data showed that bloodletting has been practiced in one form or another in many unrelated cultures, across the whole world.

Paraphernalia. (Source: Peter Merholz, CC BY-SA)

A follow-up experiment showed how stories that do not originally have any mention of bloodletting (for instance, about an accidental cut) can, when repeated over and over again, become stories about bloodletting, even among individuals with no cultural experience of bloodletting.

These results cannot be explained by bloodletting’s medical efficiency (since it is harmful), or by the perceived prestige of western physicians (since many of the populations surveyed had no exposure to them). Instead, the cultural success of bloodletting is due to the fact that it chimes with our naïve biology, and in particular with our intuitive ideas of vitalistic causality.

Bloodletting is a natural response to a naïve belief that the individual’s life force has been polluted in some way, and that this pollution must be removed. Anti-vaccination beliefs are a natural complement to this: vaccinations are a potential poison that must be kept from the body at all costs.

At an intuitive, naïve level we can all identify with these beliefs. That is why they can satirised in mainstream entertainment.

In Stanley Kubrick’s great comedy Dr. Strangelove, the American general Jack D. Ripper explains to Lionel Mandrake, a group captain in the Royal Air Force, that he only drinks “distilled water, or rainwater, and only pure grain alcohol”, because, he believes, tap water is being deliberately infected by Communists to “sap and impurify all of our precious bodily fluids”. The joke works because Ripper’s paranoia is directed at something we all recognise: the need to keep our bodies free from harmful, alien substances. Anti-vaxxers think they are doing the same.

The ConversationThis article was originally published on The Conversation. (Reblogged by permission). Read the original article.


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