When do we stop vaccinating against an infectious disease?

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.

Until 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.

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

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.

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

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

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.

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

How vaccines change the way we think about disease

By Elena Conis, Emory University

The news on the current measles outbreak contains plenty of reminders that measles causes brain damage, pneumonia, hearing loss and death. A few lone voices have spoken up to say measles isn’t that serious, including an Arizona doctor who said it’s “really just a fever and a rash” – and soon found himself under investigation by his state’s medical board.

Back in the 1960s, it wasn’t controversial to call measles benign. Though the disease killed about 400-500 Americans a year, it was considered a normal part of childhood. It was so common, in fact, that to this day, people born in the pre-measles vaccine era are considered immune. But the introduction of the measles vaccine, and efforts to promote it, fundamentally changed things. In the five decades since we’ve been immunizing against it, measles has become increasingly known as a deadly killer.

This transformation in perception, from relatively benign to a serious disease, isn’t unique to measles. As I have discovered in my research, it’s a pattern that’s been repeated over and over again in the modern history of immunization. This is not to say that measles is now considered a mild infection, or to suggest that risk from the virus, or other vaccine-preventable diseases, is overestimated. The point I want to argue is that the introduction of a vaccine reframes our perception of the disease it prevents.

Vaccines change our perception of risk

How does this happen? New vaccines simultaneously drive down the number of people getting the disease and increase our awareness of the risks of the disease.

Vaccines shine a spotlight on their target infections and, in time, those infections — no matter how “common” or relatively unimportant they may have seemed before — become known for their rare and serious complications and defined by the urgency of their prevention.

A spotted vaccine delivery van labeled ‘Measles must go.’ Source: CDC

This certainly happened to measles, whose first vaccine was uneventfully released in 1963.

At the time, many parents saw measles as a common and relatively harmless part of childhood – even though it infected three to four million people a year and caused roughly 48,000 hospitalizations annually. Many doctors felt as parents did, especially when comparing measles to such worrisome disease threats as smallpox and polio. Even the head of the Centers for Disease Control described measles as a disease “of only mild severity” which caused “infrequent complications.”

But the very development of the vaccine focused new scientific attention on the disease. Within a few years, scientists had compared measles to polio — the previous decade’s public health priority — and found it a much more serious threat to children’s health. Inspired by this finding, and frustrated by the public’s lack of enthusiasm for the vaccine, federal health officials launched a national campaign to publicize measles’ dangers.

The campaign officially spread the word, for the first time, that measles was “a serious disease that sometimes causes pneumonia, deafness, encephalitis and even death.” Public figures ranging from the Surgeon General to Ann Landers announced that measles could leave children blind, deaf and mentally impaired. And the campaign employed a poster child — disabled ten-year-old Kim Fisher — to illustrate the idea that measles immunization was necessary because “one death, one brain-damaged child, or even one child who needs hospitalization is one too many,” as one campaign supporter put it.

A new picture of measles emerges

As the campaign wore on, scientists continued to study the disease more closely than ever. Doctors began to report measles cases to health departments at unprecedented rates. And together, doctors and scientists began to pay more attention to the disease’s risks than even before. As a result, a new picture of the disease began to form: it appeared to cause more deaths than previously thought, brain damage in even mild cases, even harm to fetuses.

As the public continued to respond to the national campaign with “general apathy,” however, health officials redoubled their efforts to publicize measles’ “dramatic aspects,” and states began passing laws requiring the vaccine for schoolchildren. Within just over a decade, the country saw an all-time low of measles cases — and the disease had solidly acquired its new reputation as a deadly infection worthy of prevention at any cost.

A measles immunization campaign poster display at the Eradicate Measles Exhibit in 1972. Source: CDC/Don Lovell

We used to think mumps and chickenpox were ‘mild’ too

In the decades that followed the introduction of the measles vaccine, vaccine makers and health officials duplicated this approach with one new vaccine after another.

Mumps, often the butt of jokes in its pre-vaccine days, was no laughing matter within a decade of its vaccine’s introduction in 1967. Hepatitis B was considered an obscure infection of little import to most Americans when its vaccine first came out in 1981, but soon after it evolved into a “cousin” of AIDS known for lurking in nail salons, piercing parlors and playgrounds.

Since the development of the chickenpox vaccine in the 1990s, the virus has been transformed in the public imagination from an innocuous if uncomfortable rite of childhood to a highly contagious infection that can cause pneumonia, sepsis and sometimes death. And in just the last decade, human papillomavirus (HPV) has morphed from a little-known sexually transmitted infection to a widely known cause of multiple forms of cancer. Each of these transformations in perception was triggered by a new vaccine.

Each new vaccine invited deliberation on how it should be used. That, in turn, focused increased scientific attention on the disease. Often, as federal health officials and other scientists accumulated new information about the disease’s risks and complications, the vaccine maker did its part to market its vaccine. As talk of each disease and its more dramatic aspects spread, public and scientific perception of the disease gradually transformed.

In this country, high vaccination rates rest on a consensus about the diseases prevented by vaccines. When doctors, health officials and, in particular, parents view a disease as serious, they view its vaccine as one worth getting.

The recent increase in the number of philosophical objectors to measles vaccine shows that historical consensus about the disease itself has eroded in recent years. But history also shows that one surefire route to consensus about a disease is fear of that disease. And fear often spreads like wildfire during disease outbreaks, much like what is happening once again now with measles.

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

Six myths about vaccination – and why they’re wrong

By Rachael Dunlop, University of Technology, Sydney

Recently released government figures show levels of childhood vaccination have fallen to dangerously low levels in some areas of Australia, resulting in some corners of the media claiming re-ignition of “the vaccine debate”.

You can check how your postcode rates here.

Well, scientifically, there’s no debate. In combination with clean water and sanitation, vaccines are one of the most effective public health measures ever introduced, saving millions of lives every year.

Those who claim there is a “debate” will cite a series of canards designed to scare people away from vaccinating, but, if you’re not familiar with their claims, you could easily be convinced by anti-vaccine rhetoric.

So what is true and what is not?

Let’s address just a few of the common vaccine myths and explain why they’re wrong.

1. Vaccines cause autism

The myth that vaccines are somehow linked to autism is an unsinkable rubber duck. Initiated in 1998 following the publication of the now notorious Lancet paper, (not-a-Dr) Andrew Wakefield was the first to suggest that the measles mumps rubella (MMR) vaccine might be linked to autism.

What he didn’t reveal was that he had multiple conflicts of interest including that he was being paid by lawyers assembling a class action against the manufacturers of MMR, and that he himself had submitted an application for a patent for a single measles vaccine.

It eventually unravelled for Wakefield when the paper was retracted in 2010. He was struck from the medical register for behaviour classified as “dishonest, unethical and callous” and the British Medical Journal accused him of deliberate fraud.

But once the idea was floated, scientists were compelled to investigate, particularly when it stood to impact public health so dramatically. One of the most powerful pieces of evidence to show that there is no link between vaccines and autism comes from Japan where the MMR was replaced with single vaccines mid-1993. Guess what happened? Autism continued to rise.

We currently don’t know what causes autism. But we do know what doesn’t: vaccines. Image from shutterstock.com

After this door closed, anti-vaxers shifted the blame to thiomersal, a mercury-containing component (not be confused with the scary type that accumulates in the body). Small amounts of thiomersal were used as a preservative in some vaccines, but this never included MMR.

Thiomersal or ethyl-mercury was removed from all scheduled childhood vaccines in 2000, so if it were contributing to rising cases of autism, you would expect a dramatic drop following its removal. Instead, like the MMR in Japan, the opposite happened, and autism continues to rise.

Further evidence comes from a recently published exhaustive review examining 12,000 research articles covering eight different vaccines which also concluded there was no link between vaccines and autism.

Yet the myth persists and probably for several reasons, one being that the time of diagnosis for autism coincides with kids receiving several vaccinations and also, we currently don’t know what causes autism. But we do know what doesn’t, and that’s vaccines.

2. Smallpox and polio have disappeared so there’s no need to vaccinate anymore

It’s precisely because of vaccines that diseases such as smallpox have disappeared.

India recently experienced two years without a single case of polio because of a concerted vaccination campaign.

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 current measles epidemic in Wales where there are now over 800 cases and one death, and many people presenting are of the age who missed out on MMR vaccination following the Wakefield scare.

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.

3. More vaccinated people get the disease than the unvaccinated

Although this sounds counter-intuitive, it’s actually true, but it doesn’t mean that vaccines don’t work as anti-vaxers will conflate. Remember that no vaccine is 100% effective and vaccines are not a force field. 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. Image from shutterstock.com

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.

4. My unvaccinated child should be of no concern to your vaccinated one

Vaccination is not just a personal issue, it’s a community responsibility, largely because of a concept known as “community immunity”. This describes a level of vaccination that prevents epidemics or outbreaks from taking hold and spreading.

Some people question the validity of this concept, sometimes referred to as herd immunity, but the impact of it breaking down can be easily observed in places where vaccination levels fall dangerously low – take the current measles outbreak in Wales, for example.

The other important factor about community immunity is it protects those who, for whatever reason, can’t be vaccinated or are not fully vaccinated. This includes very young children, immunocompromised people (such as cancer sufferers) and elderly people.

5. Vaccines contain toxins

A cursory search of Google for vaccine ingredients pulls up a mishmash of scary-sounding ingredients that to the uninitiated can sound like “franken-science”.

Some of these claims are patently untrue (there is no anti-freeze in vaccines), or are simple scaremongering (aborted foetuses – in the 1960s some cells were extracted from a foetus to establish a cell line that is still used in labs today). Some of the claimed chemicals (and remember everything is made of chemicals) are present, but are at such low levels as to never reach toxicity.

A pear has 600 times more formaldehyde than a vaccine. Image from shutterstock.com

The simple thing to remember is the poison is in the dose – in high enough doses even water can kill you. And there’s 600 times more formaldehyde in a pear than a vaccine.

Also, if you ever read the claim that “vaccines are injected directly into the blood stream” (they’re not), be sceptical of any other claims made.

6. Vaccines will overwhelm kids’ undeveloped immune systems

The concept of “too many too soon” was recently examined in a detailed analysis of the US childhood immunisation schedule by The Institute of Medicine. Experts specifically looked for evidence that vaccination was linked to “autoimmune diseases, asthma, hypersensitivity, seizures, child developmental disorders, learning or developmental disorders, or attention deficit or disruptive disorders”, including autism. The researchers confirmed that the childhood vaccination schedule was safe.

The amount of immune challenges that children fight every day (between 2,000 to 6,000) in the environment is significantly greater than the number of antigens or reactive particles in all their vaccinations combined (about 150 for the entire vaccination schedule).

So the next time you hear these myths about vaccination, hopefully you’ll have some evidence up your sleeve to debunk them.

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