The Flu Vaccine Is Up To 99 Per Cent Ineffective

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Research shows for every 100 healthy adults vaccinated against influenza, 99 get no benefit. So is it even worth getting? Let's look at the science.

Winter has started, and with it, flu season. Inevitably, all of us (young, old and sick) have been implored to be immunised against influenza, with some eligible for a subsidised vaccine. And people are heeding the message, to the point that there is now a shortage of available vaccines.

At the same time, findings from three important Cochrane reviews on the effectiveness of the influenza vaccination aren’t consistent with the advice we’re been given.

Cochrane reviews are independent systematic reviews, which are comprehensive analyses of most of the literature relevant to a research topic. Cochrane reviews summarise the results in a multitude of studies, and are regularly updated to absorb new research.

These three Cochrane reviews have been recently updated, as well as stabilised, which is what happens when it looks as if it seems unlikely new research would be published that would change the conclusions.

What the reviews found

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 1,000 to 9 cases out of 1,000.

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

The infection rate in adults drops from 2% per year to 1%. You could say that’s halved, but it effectively only drops by 1%. So this means that out of every 100 healthy adults vaccinated, 99 get no benefit against laboratory confirmed influenza.

The second Cochrane review – which looked at trials in children over single influenza seasons in the US, Western Europe, Russia, and Bangladesh between 1984 and 2013 – found similar results.

The third Cochrane review looked at vaccines for the elderly in nursing homes. It found much less good evidence, with only one randomised trial – considered the gold standard in clinical trials as it establishes causation rather than correlation.

While observational studies (that draw inferences from a population to establish associations) have been done to show benefits of the vaccines, bias means we cannot rely on their results.

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).

Why are we so scared of the flu?

There is a special concern about influenza from a public health point of view. This comes about from its potential to cause pandemics. The first in modern history was the Spanish influenza pandemic of 1918-19, when tens of millions of people died worldwide.

There have also been 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.

Public health experts worry about another pandemic that can be more harmful and contagious, which could be devastating. But it’s important to note the vast majority of deaths from Spanish influenza were from secondary bacterial infections and predated the antibiotic era.

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.

So what, if not the vaccine?

There are physical barriers that can 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 ConversationThere is now reasonable evidence such measures reduce infections considerably. It might take a bit of effort to change the psyche of Australians to make wearing a facemask acceptable if you have an acute respiratory infection. Even the heroic “soldiering on to work” (or school) with your virus needs to be reversed as a public health act.

Chris Del Mar, Professor of Public Health and Peter Collignon, Professor, infectious diseases and microbiology, Australian National University

This article was originally published on The Conversation.


Comments

    Be careful with inflammatory headlines such as this. Sure you get clicks, but the results will be morphed for anti-vaxxers, a point raised on the original article's comments. The article itself is written with a given slant, but that same logic applies to other conditions that affect only 1% of the population (which is a HUGE number in terms of lives and cost). A 50% reduction in that is huge. Expected better from lifehacker.

    Lies, damn lies and statistics? Since the vaccine reduces the incidence of flu infections by 50% your headline is misleading.

    If it's 50% effective against those infected, then it's 50% ineffective against those infected. 99% ineffective at fighting a non-existent infection because it can't fight what doesn't exist in 98% of the population. Now that's a bvllshite statistic for a headline.

      Agreed. A reduction from 23 in a thousand to 9 in a thousand sounds amazing. Or put the stats another way:
      Do I want a 23 in a thousand chance of getting the flu or a 9 in a thousand chance with the flu shot? Flu shot, please.
      The researchers don't seem to understand there own numbers. (Though I suspect this is another case of headlines being re-written by marketers, not journalists.)

      I agree, I have driven over 1000 days with my seatbelt, and it hasn't saved my life once (I haven't had a crash). So by using the argument in this article, I may as well not use a seat belt as its over 99% ineffective, and instead I could just wear a helmet in the car as a physical barrier to the death thing.

    So the article is posted by "Chris Del Mar and Peter Collignon", but are they responsible for the click bait headline is that lifehacker's contribution?

      The flu vaccine is being oversold – it’s not that effective Original title.

    half the country are employed as casuals with no real job security. Don't work, don't get paid. Until that changes the spread will continue i think.

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