The 2019 flu shot isn’t perfect – but it’s still our best defence against influenza



Early indications are that the vaccine has been a reasonably good match in the 2019 season.
Shutterstock

Lauren Bloomfield, Edith Cowan University

Over recent months, reports of “a horror flu season” causing serious illness and death have dominated the headlines.

The high number of cases has led some people to question the effectiveness of the flu vaccine, and whether it’s worth getting if it doesn’t guarantee you won’t get the flu.

The flu vaccine is designed to cover the strains of the flu anticipated to circulate during the season. But even with the most sophisticated scientific processes, determining the right strains to include in the vaccine isn’t 100% foolproof.




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When’s the best time to get your flu shot?


Sometimes the virus undergoes major genetic changes or “mutations” in a relatively short space of time. Reports of a “mutant strain” this year means there’s concern some people might catch a strain the vaccine hasn’t protected against.

It’s too soon to tell the full extent of the effects of this mutation on how well the vaccine has worked. But the 2019 vaccine is showing early signs of being a good match for the common strains of the flu circulating this season.

What’s in a name?

Influenza or “flu” isn’t just one virus; different strains circulate each season.

Flu viruses that cause seasonal epidemics in humans fit under one of two major groups: influenza A or B.

Most flu vaccines protect against four strains of influenza.
Image Point Fr/Shutterstock

Influenza A is further broken down into strains or subtypes based on surface proteins called hemagglutinin (H) and neuraminidase (N).

We’re currently concerned about two subtypes which cause outbreaks in humans: A/H1N1pdm09 and A/H3N2.

Influenza B viruses are similarly categorised into strains based on two distinct lineages: B/Yamagata and B/Victoria.

Understanding the circulating strains is important because it gives us clues as to which age groups will likely be worst affected. Influenza A/H3, for example, has historically been associated with higher rates of disease in people aged 65 and over.

But the circulating strains are also important because they inform how the vaccine will be developed. A good match between the vaccine strains and what is circulating will mean the vaccine offers the best possible protection.

So how do we decide which flu strains are covered by the vaccine?

Every year, a new vaccine is produced to cover the strains that are predicted to be circulating in the northern and southern hemispheres. The World Health Organisation (WHO) uses a range of measures to determine which strains should be included in the vaccine.

Many of us who were vaccinated this year would have received a quadrivalent vaccine. This means it covered four strains in total: two strains of influenza A, and two strains of influenza B.

People aged 65 and over are offered a “high-dose” trivalent vaccine, which covers both A strains, and one B strain.




Read more:
High-dose, immune-boosting or four-strain? A guide to flu vaccines for over-65s


The Australian Influenza Vaccine Committee (AIVC) reviews the results and makes recommendations for the Australian vaccine, which in 2019 covered the following strains:

  • an A/Michigan/45/2015 (H1N1)pdm09-like virus
  • an A/Switzerland/8060/2017 (H3N2)-like virus
  • a B/Colorado/06/2017-like virus (Victoria lineage) – not included in the trivalent vaccine recommendation
  • a B/Phuket/3073/2013-like virus (Yamagata lineage).

Do we always get it right?

The basic premise of forecasting is that it’s a “best guess”. It’s a highly educated guess, based on analysis and evaluation, but it’s not a guarantee.

The effectiveness of a vaccine depends on a number of factors, only some of which are within our control. While the choice for the vaccine is made on the best evidence available at the time, the viruses circulating in the population undergo changes as they replicate, known as antigenic “drift” and “shift”.

Flu viruses change every year so researchers have to make an educated guess about which ones might circulate.
Image Point Fr/Shutterstock

If the changes are only small, we can still get good cross-protection.

Less frequently, a big genetic “shift” happens. If this occurs after vaccine development has started and the strains have been chosen, we are dealing with a so-called “mutant flu” and the vaccine will likely not be a good match.

So is this year’s vaccine is working?

Data available for this year are showing the majority of influenza cases in Australia have been influenza A – with some states reporting more H3N2 than H1N1, and others reporting a more even mix of both.

The WHO Collaborating Centre in Victoria is also reporting that the majority of specimens of all four strains they’ve tested this year appear to be similar to the vaccine strains.




Read more:
We can’t predict how bad this year’s flu season will be but here’s what we know so far


While early indications are that the vaccine has been a good match in the 2019 season, the WHO Collaborating Centre has also recently confirmed there has been a mutation in the A/H3N2 strain this season.

It’s not clear yet if this mutation will have a significant impact on vaccine effectiveness, but it may at least partially explain the high case numbers we’ve seen so far.

Large vaccine effectiveness studies done at the end of the flu season will help assess the impact of this mutation. In the meantime, a mismatch on only one strain means the vaccine will still provide reasonable protection against other circulating strains.

It’s still worth being vaccinated

In the same way wearing a seat belt is no guarantee we won’t be injured in a car accident, a flu vaccine is no guarantee we won’t develop influenza this season.

A person’s underlying susceptibility, due to factors such as their age and health, will also influence how well a vaccine works.




Read more:
Kids are more vulnerable to the flu – here’s what to look out for this winter


But the flu shot remains a safe and reasonably effective strategy to reduce your risk of serious illness.

While flu epidemics remain complex, advice to prevent flu transmission remains simple. Regularly washing our hands, covering our mouth when we cough or sneeze, and staying home when we’re unwell are things we can all do to help stop the spread.The Conversation

Lauren Bloomfield, Lecturer, School of Medical and Health Sciences, Edith Cowan University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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You can’t get influenza from a flu shot – here’s how it works


You might feel a bit off after your flu shot but this doesn’t last long.
Rawpixel.com/Shutterstock

Allen Cheng, Monash University and Katherine Kedzierska, University of Melbourne

Influenza is a moving target for vaccines. Each year, up to four different strains circulate, and they are constantly evolving to escape our immune system.

So rather than childhood jabs giving long lasting immunity, we need annual flu shots to provide optimal protection against influenza.

But while you might sometimes get sick after having a flu shot, it’s a myth that having a flu shot can give you the flu.

A quick history of the flu vaccine

Influenza vaccines were first developed in the 1930s and 1940s, starting with the isolation of the influenza virus.

Back then, we learned there were many different influenza strains. To be effective, early research showed the vaccine needed to be matched to the circulating strains, and to be able to stimulate a response from the immune system.




Read more:
When’s the best time to get your flu shot?


The process to produce modern influenza vaccines now occurs on a much more refined and industrial scale. Hundreds of thousands of influenza viruses are collected by hundreds of national influenza centres around the world.

From these, four strains are selected for the annual flu vaccine, based on the viruses that are circulating at that time, how well the vaccines activate the immune system, how the strains are evolving, and the effectiveness of previous vaccines.

Modern flu vaccine development is slow and labour-intensive process.
hotsum/Shutterstock

Most modern vaccines are manufactured by growing large quantities of live virus – mostly in chicken eggs or less commonly animal cells – which are then purified, deactivated and split into smaller components. These vaccines are inactive and cannot replicate.

There are also two new “enhanced” vaccines that are used in older people, who don’t tend to respond as strongly to vaccines: Fluzone High Dose and Fluad, which is designed to better stimulate immunity and draw immune cells to the site of vaccination.




Read more:
High-dose, immune-boosting or four-strain? A guide to flu vaccines for over-65s


How the immune system fights the flu

The human immune system has several strategies to protect against infection. For viral infections such as influenza, the key strategy is known as adaptive immunity. This part of the immune system can “remember” previous exposure to pathogens.

When you get an influenza infection, the virus enters and hijacks the machinery of the host cell to replicate itself, before releasing these copies to infect more cells.

T lymphocyte cells of the immune system can recognise this viral incursion. T cells protect against further spread of the virus by activating pathways that cause infected cells to trigger a “suicide” process.

Another strategy the body uses is to produce antibodies, which are molecules produced by B cells that recognise components of the viral capsule. These antibodies work by sticking to the surface of the influenza virus to prevent it spreading and facilitating disposal.

Flu shots help mount a quicker defence

On a first exposure to a pathogen, our B cells take at least two weeks to ramp up production of antibodies. However, on subsequent challenges, antibody production occurs much more quickly.

Influenza vaccines harness this arm of the immune system, known as “humoral” immunity. By “practising” on viral components, vaccines allow the immune system to react more quickly and effectively when faced with the real virus.

The flu shot takes about two weeks to start protecting you against influenza.
DonyaHHI/Shutterstock

So why do you sometimes get sick after a flu shot?

There are several reasons why you might feel a bit off after getting your flu shot.

First, your flu shot only protects you against influenza and not other respiratory illness which might causes similar cold or flu symptoms. This includes RSV (respiratory syncytial virus), which is common in late autumn and early winter.




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Sick with the flu? Here’s why you feel so bad


Second, stimulating the immune system can result in symptoms similar to that of influenza, although much milder and short-lived. These include local inflammation (redness, pain or swelling at the site of the vaccine) and more general symptoms (fever, aches and pains, tiredness).

Third, vaccine-induced protection isn’t complete. In some years, the vaccine is not well matched to circulating strains. Usually this is due to mutations that may develop in circulating strains after the vaccine strains are selected.

The flu vaccine also doesn’t “kick in” for two weeks after vaccine administration. In some people, particularly those who are older and those who have weakened immune systems, antibody production is not as strong, and the level of protection is lower.

Despite this, studies have consistently shown that vaccinated people are less likely to get influenza or complications from the flu than those who aren’t vaccinated.




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Flu vaccine won’t definitely stop you from getting the flu, but it’s more important than you think


A better way to protect against the flu

A problem with current vaccines is the reliance on eggs, which results in a relatively slow and labour-intensive production process.

Current work is aiming to speed up this process by using different technologies so that vaccine manufacturers can react more quickly to changes in circulating viruses.

The “holy grail” for influenza vaccines is to stimulate an effective immune response to a component of influenza that doesn’t change each year, so annual vaccination is not required.

These efforts have proved elusive so far.




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The Holy Grail of influenza research: a universal flu vaccine


A better strategy might be to harness T cell immunity. Recent work has shown that a type of T cell, known as “killer” T cells, can recognise other parts of the influenza virus, and therefore can provide broad protection against seasonal and pandemic strains.

But while we wait for a better alternative, getting an annual flu shot is the best way to avoid the flu.The Conversation

Allen Cheng, Professor in Infectious Diseases Epidemiology, Monash University and Katherine Kedzierska, Academic, Microbiology and Immunology, University of Melbourne

This article is republished from The Conversation under a Creative Commons license. Read the original article.

When’s the best time to get your flu shot?



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What goes up must come down, and that includes the protection the flu vaccine offers against influenza.
Irina Bg/Shutterstock

Ian Barr, WHO Collaborating Centre for Reference and Research on Influenza

When most of us get the flu, we spend three or four days on the couch feeling miserable, then we bounce back pretty quickly. But others have more severe symptoms and need to be hospitalised because they’re at risk of life-threatening complications. Some people even die from the flu.

The size and impact of influenza seasons varies from year to year. In 2017, Australia had its worst flu season for 20 years, with at least 1,255 lives lost. The 2018 season was relatively mild, but it doesn’t seem to have ever ended – cases have been reported throughout summer and into autumn 2019.

The best way to protect against influenza is to get a flu vaccine each year. It’s not as effective as some other vaccines, but it reduces your risk of getting the flu by around 60%.




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Protection often will have begun to wane four or five months later, so getting vaccinated in mid to late May, or even early June, will give you better protection at the height of the flu season. But there are number of factors to consider before deciding when to get your flu shot.

Remind me, why get a flu shot each year?

Influenza viruses change each year and the vaccine is updated to keep up with these changes. This year, for example, the vaccine protects against two different strains than the 2018 vaccine.

Our body’s immune response to the vaccine also wanes over time. So even if you were vaccinated last winter, you may no longer be fully protected 18 months later, depending on your age and your response to the last vaccination.

When does the flu vax become available?

Influenza vaccines are usually available in early April, or even in March; though you’ll generally have to pay full price for early access, even if you’re eligible for a free flu vaccine later.

In mid-April, stock starts arriving at GP clinics and pharmacies for the government’s immunisation program, which offers free flu vaccines for those most at risk of complications from influenza. This includes:

  • all Aboriginal and Torres Strait Islander people aged six months and over
  • pregnant women (during any stage of pregnancy)
  • all people aged 65 years and over
  • people aged six months and over with medical conditions which increase the risk of complications following influenza infections.



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Should I get the flu shot if I’m pregnant?


In addition, most states in Australia offer free vaccination to all other children from six months of age to five years of age.

For those not eligible for the free vaccine, influenza vaccines are available through pharmacies and GPs for between A$10 and A$25 (plus the cost of a consultation if your GP doesn’t bulk bill), or via workplace programs.

The 2018 flu season was mild but there have been more cases of influenza over summer than usual.
kurhan/Shuttestock

Is it good to get in early?

Getting a vaccine immediately after it becomes available will ensure you don’t miss out if there’s a vaccine shortage. And it will protect against the “summer flus” we’ve been seeing over the last few months, which are circulating earlier than normal.

But there is a potential downside. Protection against influenza peaks one to two months after you have your vaccine, and then declines. This rate of decline varies from person to person, by age, and by influenza strain.

The flu season usually reaches its peak in August or sometimes even September. So if you’re vaccinated in early April, four to five months will have passed by the time you reach the peak virus months, and you will have lower levels of protection.




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Flu vaccine won’t definitely stop you from getting the flu, but it’s more important than you think


There are few good quality studies across all ages to measure this rate of decline accurately, although a study from 2015 showed that the measurable antibody responses to the influenza vaccine components reduced slowly.

Another study from 2014 showed the vaccine was less effective in people vaccinated three or more months earlier, adding to the evidence that protection wanes over time.

When is too late for the flu shot?

If you delay your decision to be vaccinated until July or August, when the flu season is well underway, your chance of becoming infected will significantly increase.

Mid to late May or early in June is the sweet spot between trying to maximise your protective levels of antibodies generated by vaccination and getting vaccinated before there are significant levels of influenza virus circulating.

It’s better to be vaccinated early than not at all.
DonyaHHI/Shutterstock

Remember, it takes seven to ten days from the time of your flu shot for the vaccine to begin to be fully effective.

Getting vaccinated in late May or early June should provide good levels of protection during the peak of the influenza season and may even last through to November, by which time the influenza season has usually finished.

Vaccinate kids a month earlier

Vaccination timing is a little different for children. Those aged six months to nine years who haven’t been vaccinated against influenza before need two doses of vaccine, four weeks apart. So they will need to start their vaccination program a month earlier than adults and the elderly.




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


So if you want to get vaccinated in 2019, there’s no need to rush, and in fact May or even early June might be a better time to be vaccinated. But it’s better to be vaccinated early than not at all.

Your GP or pharmacist will advise you on the most appropriate vaccine and the best timing for you.The Conversation

Ian Barr, Deputy Director, WHO Collaborating Centre for Reference and Research on Influenza

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Everyone can be an effective advocate for vaccination: here’s how


File 20190219 121729 4lwlw3.jpg?ixlib=rb 1.1
Listening to people’s concerns is important when talking to someone who is hesitant about vaccination.
From shutterstock.com

Jessica Kaufman, Murdoch Children’s Research Institute and Margie Danchin, Murdoch Children’s Research Institute

The World Health Organisation (WHO) has named vaccine hesitancy as one of their top 10 threats to global health for 2019.

Last week, the wife of an NRL footballer made national headlines after posting on Instagram that the couple did not plan to vaccinate their children.

Indeed, there’s rarely a time vaccination isn’t a hot topic of public debate. What’s important to note is that anyone can use evidence-based communication techniques to be an advocate for vaccination – you don’t need to be an expert in the field.

Conversations between peers can be very influential, because our behaviours are shaped by social norms, or what other people in our network value and do.




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Who do we need to talk to?

While the current measles outbreaks in the United States and Europe are concerning, much of the reporting has over-simplified the issue, with sensationalised headlines placing the blame almost solely on “anti-vax” parents.

In reality, the vast majority of people whose children are missing some or all doses of the recommended vaccines are not “anti-vaxxers”, and labelling them as such is unhelpful.

The ability to register for vaccination exemption based on conscientious objection was removed in 2016, but it was last recorded in December 2015 as affecting only 1.34% of eligible children.

Current childhood vaccination coverage in Australia is between 90.75-94.67%, depending on age.

This suggests that missed opportunities and access barriers, such as parents being unable to get to the GP or a council immunisation session, are much more substantial contributors to under-vaccination.

Under-vaccination is regarded as a threat to global health.
From shutterstock.com

Communication about vaccines is unlikely to impact the behaviour of firm refusers and those facing access barriers. However, communication has enormous influence when it comes to the 43% of parents who have some questions or concerns about vaccines.

Aggressive or dismissive language can make people less likely to vaccinate, while open, respectful discussion with a trusted individual can encourage hesitant parents towards vaccination.




Read more:
Want to boost vaccination? Don’t punish parents, build their trust


Tips for discussing vaccination

Many people struggle with how to discuss vaccination when confronted with a friend, relative or acquaintance who expresses hesitancy.

Simply providing lots of facts or dismissing their views is not effective.

Instead, these are some tips everyone can use when talking about vaccines, drawing from evidence-based communication techniques. Studies in the United States and Canada have trained healthcare providers to use techniques like these to increase uptake of adolescent HPV vaccination and infant vaccines, and more studies are currently underway.

Ask about, and listen to, people’s concerns: not everyone is driven by the same issues or experiences. Find out what specifically is concerning the person. Is it safety? Effectiveness? Side effects?

Acknowledge their concerns: remember, everyone loves their children. No one is refusing to vaccinate because they want their child to get sick, or because they wilfully hope other children will get sick. Acknowledging that you see where someone is coming from can go a long way in establishing trust.

Provide information to respond to their concerns: share what you know, and try to provide reliable sources for your information. Be careful not to debunk myths too aggressively, as this can actually backfire.

Share personal stories: emotive stories tend to have more impact than facts. This is one reason stories of rare vaccine adverse events can seem to carry more weight than overwhelming safety figures. Share your own stories of positive experiences with vaccines, or better yet, discuss your experience with the diseases they prevent.

Don’t pass judgment: people may discuss vaccination many times with many different people before they decide to vaccinate, especially if they are very hesitant. Your goal should be to establish yourself as a trusted, non-judgmental person with whom they can share their questions and concerns. Berating them won’t convince them to vaccinate, but it will convince them never to speak to you about vaccines again.




Read more:
Australians’ attitudes to vaccination are more complex than a simple ‘pro’ or ‘anti’ label


These communication tips can help support discussions about vaccines with someone who is hesitant, but open to discussing their position. If, however, you find yourself publicly debating a “vocal vaccine denier”, the WHO has developed a toolkit to help guide your responses.

In such a situation, your intended audience is not the vaccine denier themselves, but the public who may be watching or reading your debate.

The techniques used by a vaccine denier could include referring to conspiracies, fake experts, selective or misrepresented evidence, or impossible expectations (such as 100% safety). The WHO recommends you identify the techniques the denier uses and then correct their content.

If you’re a strong supporter of vaccination, you can become a powerful ally in the effort to sustain high coverage rates in your community. Listen and share your views respectfully, build and maintain open and trusting relationships, and yours may be the words that encourage another person to vaccinate.The Conversation

Jessica Kaufman, Postdoctoral researcher in vaccine acceptance and communication, Murdoch Children’s Research Institute and Margie Danchin, Senior Research Fellow and General Paediatrician, Murdoch Children’s Research Institute

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Most people don’t benefit from vaccination, but we still need it to prevent infections



File 20180608 137312 1kiqzuz.jpg?ixlib=rb 1.1
Everyone has to be vaccinated for immunisation programs to work.
from http://www.shutterstock.com

Allen Cheng, Monash University

A recent article in The Conversation questioned whether we should all get flu vaccinations, given 99 people would have to go through vaccination for one case of flu to be prevented.

But this position ignores the purpose of immunisation programs: whole populations of people need to take part for just a small number to benefit. So how do we decide what’s worth it and what’s not?




Read more:
The flu vaccine is being oversold – it’s not that effective


Decision-making in public health

When we consider a treatment for a patient, such as antibiotics for an infection, we first consider the evidence on the benefits and potential harms of treatment. Ideally, this is based on clinical trials, where we assume the proportion of people in the trial who respond represents the chance an individual patient will respond to treatment.

This evidence is then weighed up with the individual patient. What are the treatment options? What do they prefer? Are there factors that might make this patient more likely to respond or have side effects? Is there a treatment alternative they would be more likely to take?

In public health, the framework is the same but the “patient” is different – we are delivering an intervention for a whole population or group rather than a single individual.

We first consider the efficacy of the intervention as demonstrated in clinical trials or other types of studies. We then look at which groups in the population might benefit the most (such as the zoster vaccine, given routinely to adults over 70 years as this group has a high rate of shingles), and for whom the harms will be the least (such as the rotavirus vaccine, which is given before the age of six months to reduce the risk of intussusception, a serious bowel complication).

Compared to many other public health programs, immunisation is a targeted intervention and clinical trials tell us they work. But programs still need to target broad groups, defined by age or other broad risk factors, such as chronic medical conditions or pregnancy.




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Risks and benefits of interventions

When considering vaccination programs, safety is very important, as a vaccine is being given to a generally healthy population to prevent a disease that may be uncommon, even if serious.

For example, the lifetime risk of cervical cancer is one in 166 women, meaning one woman in 166 is diagnosed with this cancer. So even if the human papillomavirus (HPV) vaccine was completely effective at preventing cancer, 165 of 166 women vaccinated would not benefit. Clearly, if we could work out who that one woman was who would get cancer, we could just vaccinate her, but unfortunately we can’t.

It’s only acceptable to vaccinate large groups if clinically important side effects are low. For the HPV vaccine, anaphylaxis (a serious allergic reaction) has been reported, but occurs at a rate of approximately one in 380,000 doses.

An even more extreme case is meningococcal vaccination. Before vaccination, the incidence of meningococcal serogroup C (a particular type of this bacterium) infection in children aged one to four years old was around 2.5 per 100,000 children, or 7.5 cases for 100,000 children over three years.

Vaccination has almost eliminated infection with this strain (although other serotypes still cause meningococcal disease). But this means 13,332 of 13,333 children didn’t benefit from vaccination. Again, this is only acceptable if the rate of important side effects is low. Studies in the US have not found any significant side effects following routine use of meningococcal vaccines.

This is not to say there are no side effects from vaccines, but that the potential side effects of vaccines need to be weighed up against the benefit.

For example, Guillain Barre syndrome is a serious neurological complication of influenza vaccination as well as a number of different infections.

But studies have estimated the risk of this complication as being around one per million vaccination doses, which is much smaller than the risk of Guillain Barre syndrome following influenza infection (roughly one in 60,000 infections). And that’s before taking into account the benefit of preventing other complications of influenza.




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Is the end of Zika nigh? How populations develop immunity


High schools are bigger, so immunisation is easier than at primary schools.
from http://www.shutterstock.com

What other factors need to be considered?

We also need to consider access, uptake and how a health intervention will be delivered, whether through general practices, council programs, pharmacies or school-based programs.

Equity issues must also be kept in mind: will this close the gap in Indigenous health or other disadvantaged populations? Will immunisation benefit more than the individual? What is the likely future incidence (the “epidemic curve”) of the infection in the absence of vaccination?

A current example is meningococcal W disease, which is a new strain of this bacteria in Australia. Although this currently affects individuals in all age groups, many state governments have implemented vaccination programs in adolescents.

This is because young adults in their late teens and early 20s carry the bacteria more than any other group, so vaccinating them will reduce transmission of this strain more generally.

But it’s difficult to get large cohorts of this age group together to deliver the vaccine. It’s much easier if the program targets slightly younger children who are still at school (who, of course, will soon enter the higher risk age group).

In rolling out this vaccine program, even factors such as the size of schools (it is easier to vaccinate children at high schools rather than primary schools, as they are larger), the timing of exams, holidays and religious considerations (such as Ramadan) are also taken into account.




Read more:
What is meningococcal disease and what are the options for vaccination?


For government, cost effectiveness is an important consideration when making decisions on the use of taxpayer dollars. This has been an issue when considering meningococcal B vaccine. As this is a relatively expensive vaccine, the Pharmaceutical Benefits Advisory Committee has found this not to be cost effective.

This is not to say that meningococcal B disease isn’t serious, or that the vaccine isn’t effective. It’s simply that the cost of the vaccine is so high, it’s felt there are better uses for the funding that could save lives elsewhere.

While this might seem to be a rather hard-headed decision, this approach frees up funding for other interventions such as expensive cancer treatments, primary care programs or other public health interventions.

Why is this important?

When we treat a disease, we expect most people will benefit from the treatment. As an example, without antibiotics, the death rate of pneumonia was more than 80%; with antibiotics, less than 20%.

The ConversationHowever, vaccination programs aim to prevent disease in whole populations. So even if it seems as though many people are having to take part to prevent disease in a small proportion, this small proportion may represent hundreds or thousands of cases of disease in the community.

Allen Cheng, Professor in Infectious Diseases Epidemiology, Monash University

This article was originally published on The Conversation. Read the original article.