Tag Archives: vaccine

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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The 2015 flu vaccine – what’s new, who should get it and why

The Conversation

Aeron Hurt, WHO Collaborating Centre for Reference and Research on Influenza

It’s that time of year again when scientists and doctors make predictions about the impending influenza (flu) season and we must decide whether to go out and get the flu vaccine.

The government-funded flu vaccine will be available from 20 April, a month later than most years, as the vaccine has been reformulated to cover a new strain. But some GPs may offer the vaccine privately before then.

So, who should consider getting the vaccine and who gets it for free? And are we really in for a bad flu season in Australia?

How does the vaccine work?

The flu vaccine helps prevent us from getting the flu each season. It contains dead, broken-up bits of flu viruses that are expected to circulate during the upcoming season.

Once injected into our arms, the pieces of dead virus stimulate our body’s immune response to produce antibodies, which act as a defence that can rapidly swing into action when a live flu virus infects our nose and throat.

Because the viruses in the vaccine are dead, they can’t give us flu.

What’s new about flu vaccines in 2015?

For the first time, Indigenous children are able to access free flu vaccine in Australia.

This is important because Aboriginal and Torres Strait Islander children are five times more likely to be hospitalised with flu and pneumonia than non-Indigenous children. Indigenous children are also 17 times more likely to die from flu or pneumonia than non-Indigenous children.

Australia’s vaccine has been updated to protect against the harmful new A(H3N2) viruses. (Source: El Alvi/Flickr, CC BY)

This year a new flu vaccine, known as “quadrivalent”, will be available. This type of vaccine contains four flu viruses compared with three in the normal trivalent vaccine. The additional flu strain provides extra insurance that may be useful if unexpected viruses begin to circulate.

However, it’s likely that the standard trivalent vaccine will cover the great majority of the flu A and B strains expected to circulate in Australia this winter.

The quadrivalent vaccine won’t be available via the government’s free flu vaccine program and will be more expensive than the standard trivalent vaccine if purchasing it privately.

Who should get the flu vaccine?

For certain members of the community, catching flu can lead to severe illness or death. It is these “high-risk” groups (listed below) that should actively avoid catching it. Getting the flu vaccine is a major step towards achieving protection from flu.

Certain groups of individuals at high risk of developing severe illness or complications if infected with flu are eligible for free flu vaccine via the federal government. These are:

  • Anyone aged 65 years or over
  • Aboriginal and Torres Strait Islander people aged 15 years or over
  • Aboriginal and Torres Strait Islander children aged between six months and five years
  • Pregnant women
  • Anyone with with medical conditions that can lead to severe influenza, including people with heart disease, severe asthma and diabetes. A full list of eligible medical conditions can be found here.

Within the over-65 age group, a high proportion of people are vaccinated (more than 70%).

But although the flu vaccine is provided free of charge to vulnerable people, many still don’t get it. Less than 30% of pregnant women and Indigenous people receive the flu vaccine. Only half of those with medical conditions that can lead to severe influenza get vaccinated.

Fit, healthy children can’t always fight off a flu. (Source: Chaikom/Flickr)

Although not included in the government’s free flu vaccine program, children under the age of two years are also highly susceptible to flu.

Once infected with flu, young kids are more likely to be hospitalised with severe illness than those in the over 65 age group. About half of young children who die from the flu are otherwise healthy with no underlying medical conditions or known risk factors.

Most children who die from flu are not vaccinated. Therefore the idea that fit, healthy infants can simply “fight off” a flu infection without any problem is not always true.

Another benefit of preventing flu in children is that it reduces the spread of infections to other vulnerable family members such as grandparents.

What’s in store for us this winter?

The one predictable thing about flu, is that it is unpredictable! However, we often look to the northern hemipshere’s winter flu season to give some insights into what might be expected here.

The recent flu season in the United States and most of Europe was dominated by the A(H3N2) strain of flu. This virus has historically been associated with increased severity in the elderly.

There has been a lot of media coverage about bad vaccine match in the northern hemisphere. This is because most of the serious influenza was caused by the A(H3N2) viruses which had changed over the five to six months when the vaccine producers were manufacturing the vaccine. But the other components of the vaccine were well matched.

Our vaccine has been updated to protect Australians against the new A(H3N2) viruses.

So, if you or a loved one fall within the high-risk groups described above, getting the vaccine remains the most effective way to avoid the inconvenience and potentially severe health risks of the flu – and passing it on.

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


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