Are free flu shots targeted to the right people?
School children, sometimes described as walking ‘petri dishes,’ might be a double-whammy win for influenza reduction.
As Australia suffers a terrible season of influenza which has already killed more than 100 people, news broke New Zealand has a vaccine shortage.
Last year, 1.3 million doses of the influenza vaccine were distributed.
Just a week into this year’s flu season and 1.26 million doses have been sold and national stocks are running low.
Pharmac has said that it is unlikely more will be able to be sourced.
Health providers are now being asked to target the vaccines they have left to those most at risk.
These are pregnant women, the elderly, and those with chronic illnesses. For these people the vaccine is publicly funded.
Deaths in Auckland
To date, three Aucklanders have died from influenza: a 12-year-old, a 20-year-old and a 62-year-old, and there’s a spike in doctor visits of people suffering influenza symptoms. Annually, it is estimated that influenza kills around 500 New Zealanders, either directly or from complications such as pneumonia, or respiratory or cardiac issues.
In the 2018 flu season, majority of people hospitalised were under 65. A third were hospitalised and half of those who ended up in intensive care had no pre-existing conditions.
The previous flu season was markedly different. The influenza virus strain circulating affected older people more. In 2017, it was mostly those over 65 and with pre-existing conditions who were hospitalised.
Who responds best to the vaccine?
While a person over 65 might be most vulnerable to particular strains of influenza virus, there is a chance a vaccine won’t be as effective for them as it would be for a younger person.
As we age our immune system wanes. A 10-year-old’s body will often do a far better job developing antibodies to a virus than a 65-year-old’s body.
There’s a case to be made for immunising school-aged children to protect them as well as reduce the overall rate of influenza circulating.
University of Otago Public Health Specialist Professor Michael Baker said this is happening in some overseas countries such as the United Kingdom.
“That is a huge shift in thinking to a population protective effect.”
Unlike the measles vaccine, which is 97% effective, the yearly influenza vaccine varies in effectiveness. Influenza viruses have the ability to mutate. Each year vaccine makers try to stay one step ahead of the coming flu season and choose four strains most likely to circulate.
Sometimes this works well, other times it doesn’t.
Effectiveness rates can vary between 30 and 65 percent. Traditionally this has meant individual protection has been the focus of vaccination programmes.
“With influenza, because the vaccine is still only moderately effective, the philosophy has been to give it to the most vulnerable. The next step in thinking is you also give it to people who spread it a lot, like little kids. Then you get a population protective effect and you’re dampening down transmission, the bonus effect of protecting the recipient, and reducing circulation,” Professor Baker said.
The vaccine shortage
Pharmac is responsible for purchasing flu vaccines for the country and works with the supplier to determine the number of doses needed for the following year.
The shortage is the second time in months there has been vaccine issues. In March, Christchurch ran low on measles vaccines in the middle of an outbreak.
Unlike measles, the influenza vaccine is reformulated each year based on predicted virus strains. There’s a lead time of several months to make the vaccine.
Farah Hancock is a Newsroom Reporter based in Auckland who writes on conservation, technology and health. The above Report (is a highly edited version- full text at www.indiannewslink.co.nz) has been published under a Special Arrangement with Newsroom.
Image Courtesy: The Nelson Daily