Flu shot effectiveness questioned

Professor Chris Del Mar and Professor Peter Collignon say new vaccines must be prepared every year for a best-guess at next year’s virus.

THREE recent reviews of influenza research indicate the effectiveness of the flu vaccination is not consistent with the advice given to people about immunisation, according to health experts.

In The flu vaccine is being oversold – it’s not that effective (The Conversation, June 5) Bond University public health Professor Chris Del Mar and Australian National University infectious diseases and microbiology Professor Peter Collignon said findings from three important Cochrane reviews on the effectiveness of the influenza vaccination were not consistent with the advice given.

“Cochrane reviews are independent systematic reviews, which are comprehensive analyses of most of the literature relevant to a research topic,’’ they said.

“Cochrane reviews summarise the results in a multitude of studies, and are regularly updated to absorb new research.

The first Cochrane review looked at the effects of the influenza vaccine in healthy adults from 25 studies conducted over single influenza seasons in North America, South America, and Europe between 1969 and 2009.

“It found the vaccine reduced the chance of getting laboratory confirmed influenza from 23 cases out of 1000 to 9 cases out of 1000,’’ they said.

While this seems to be a reduction of more than 50 per cent, that seems less optimistic expressed in absolute terms.

“The infection rate in adults drops from 2 per cent per year to 1 per cent.

“You could say that’s halved, but it effectively only drops by 1 per cent.

“So this means that out of every 100 healthy adults vaccinated, 99 get no benefit against laboratory confirmed influenza.

“There are also potential harms from influenza vaccines noted in the reviews.

“They range from serious (a neurological disease called Guillain Barre) through to moderate (fevers, in children especially – some of which will cause febrile convulsions), and trivial (a sore arm for a couple of days).’’

Professor Del Mar and Professor Collignon said health authorities worried about the flu causing pandemics like the Spanish flu pandemic of 1918-19 during which tens of millions of people died worldwide.

“But it’s important to note the vast majority of deaths from Spanish influenza were from secondary bacterial infections and predated the antibiotic era.’’

“There have also been several, less severe pandemics.

“These include the most recent swine flu that, although while affecting some (unexpected) groups of people (including pregnant women, those who were obese, and had asthma), caused little more effect on the overall population than the usual seasonal influenza.

“The reasons influenza virus has this ability to cause new pandemics comes from its instability – it changes genetically easily, making it more difficult for our immune systems to recognise newer strains.

“The effect is that new vaccines must be prepared every year for a best-guess at next year’s virus, and we need vaccination every year.

“Influenza can also undergo a more radical change, such as when a new form of the virus emerges from an animal host (wild or domesticated birds or pigs, for example).

“This moving target makes it more difficult to vaccinate against – especially with the genetic shifts of pandemics.

“Just when we need protection most, vaccines can provide it least.’’

They said there were physical barriers that could prevent the spread of influenza.

“These are the masks (to reduce the spread of aerosol-borne virus particles), hand washing (to reduce the spread if virus from hands onto shared surfaces) and quarantine measures (isolating infected people to reduce their infectivity).’’

The Department of Health’s website says flu is a highly contagious disease and some people are at risk of serious health complications if they get flu.

The website said people most at risk of serious complications from flu were eligible for free flu vaccinations and that people should get vaccinated against the flu every year.

In 2018, a new vaccine is available for people aged 65 years and over,’’ the website said.

“The new vaccine has been designed to increase the immune system’s response among older adults, who are known to have a weaker response to immunisation.

“The new vaccine includes an influenza A (H3N2) strain which has the greatest impact on people aged over 65 years.

“In 2018, a two year trial starts that allows people aged over 65 years to get the flu vaccination at some pharmacies.’’

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