Why It’s Still Smart To Get A Flu Shot

Why It’s Still Smart To Get A Flu Shot

There’s a new flu shot every year, to match the particular flu strains floating around. Some years the shot isn’t a good match. Even so, the flu shot is still a good bet.

Weighing risks against benefits, flu shots still come out on top because the downsides are so minimal. A flu shot might give you a sore arm, but they don’t give you the flu (that’s a myth) and aren’t likely to have serious side effects. Against such small downsides, it only takes a small benefit to tilt the balance in favour of getting the vaccine. Here’s Julia Belluz at Vox describing how well the shot works at preventing the flu:

In kids, the highest-quality evidence — a randomised controlled trial — suggests the vaccine works well enough: On average, if you give six kids under the age of six a flu shot, you can expect to prevent one case of the flu. For children under age 2, the benefits are less clear; the evidence, the researchers found, was scant, and of the research that was available, it seemed the efficacy of the shot was similar to placebo.
In adults, however, the vaccine’s effects are more modest. “Depending on the season,” explained Tom Jefferson, an author on these Cochrane reviews, “you need to vaccinate anywhere between 33 and 100 people to avoid one set of symptoms.” In a good year, when the WHO guesses correctly and the flu shot matches the strains in circulation, you need to give 33 adults flu shots, on average, to prevent one case of illness. In a year when the WHO guesses badly, you need to vaccinate 100 people to prevent one flu case.

A good strategy is to combine a flu shot with some common-sense measures like washing your hands often during flu season, and encouraging your friends and co-workers to stay home when they’re sick. Read more at the link below, and if you still have doubts, check out this list of flu shot myths, busted.

How Well Do Flu Shots Work? Here’s What the Science Says [Vox]


  • People think they get sick from the Flu Shot, are usually getting an immune system response to the anti-gen being assimilated… the body sees flu anti-bodies and gives a false alarm and starts the human body responses to expel foreign bodies such (runny nose etc) and then goes Oops false alarm and switches off the fluid works. Its actually a good sign, it means you got an aggressive immune system.

    Most people cant tell the difference between a Cold and a Flu… get a cold, and think the flu shot failed.
    Given we dont have a cure for the Flu… vaccine is the best and only bet.

    • On the right track in general. Though a few points worth correcting:
      1. the fluvax is inactivated virus not “flu antibodies”. Hence why the immune system recognises it as an invader.
      2. the “sero-conversion sickness” people experience tends to be analogous to the systemic symptoms of flu, like muscle aches and tiredness. They shouldn’t get a runny nose … that would imply a concurrent cold.
      3. there is a “cure” of sorts for flu. Two in fact, Tamiflu and Relenza. These tend to be reserved for more severe cases where shortening the duration of illness is useful. For most people it’s not worth giving and it’s preferable just to let the illness run it’s course.

      On a side note, it’s worth noting that the flu shot is effectively a gamble. Public health have to predict which strains are expected to be prevalent in any winter many months in advance (to allow lead time for CSL to generate stock).

      So, regardless of the average NNT, it’s entirely possible for any year’s vaccinations to cover all or none of the strains that actually circulate.

  • spending your free time and money on a small chance of avoiding the flu might be your idea of a good time but it’s not mine, i think i’ve had the flu once in the last 10 years as it is

    • Right up to the point where I see you tubed in my intensive care unit with the flu. Plus most people who think they’ve had the flu and that the flu isn’t so bad, have never had the flu. The flu is not a bad cold. Considering the low cost, the convenience of getting it, the low risk of serious side effects, its very much worth it for purely selfish reasons. If you had have got the flu shot every year for 10 years, you’d still be financially ahead for having missed one less day of work from catching it. That’s even ignoring that if you do catch the flu, you won’t be off for a single day, try 1-4 weeks. Even longer if you end up in hospital. Perhaps months if you end up in ICU.
      Plus there’s always the non selfish reasons to get it. Like not killing all our elderly, young or sick friends, colleagues, family, or random strangers on the street. Herd immunity with the right flu shot helps to reduce the overall incidence among those who aren’t or can’t be vaccinated, which saves lives.

  • At what point in time do we know that “WHO guesses badly”? Are the vaccines still released even if they know it will cover none of the strains?

    • We tend to vaccinate people before the flu season hits, so we don’t know for sure what strains will be prevalent this year. Its not just guessing though. It’s based on studies of what flu strains are prevalent now, what strains have been prevalent in flue seasons internationally, and we can work out what strains are more likely to be prevalent for the upcoming flu season. Sometimes we cover all and if vaccination rates are high we have a good flu season. Sometimes we miss a bug, or the cheaper trivalent vaccines miss a bug, and we have a bad one.
      The 2015 flu season in Brisbane was a bad one, because the commonly used trivalent (3 strains) flu shot, which is what the government generally provides to health care staff and the public free of charge, didn’t cover the strain that ended up prevalent in Brisbane that season. The quadrivalent vaccine did. So this year we all got the more expensive shot.

      • I was wondering about the different coverage. My workplace offers free shots, but the tri- was available about a month earlier than the quad-. I figured it was better to get the earlier option. So far, so good.

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