Influenza vaccine effectiveness for 2017-18 season – interim CDC report

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I’ve written about 2017-18 influenza vaccine effectiveness several times over the past few months (see here and here) because of the claims, that have grown into facts, about the “useless flu vaccine.” I keep reading comments (even in articles I’ve written) that people aren’t getting the flu shot this year because it has only a 10% effectiveness.

That 10% number seems to be tied to an article published in late 2017 in Eurosurveillance, a journal focused on tracking infectious disease outbreaks. They derived their number from a very conservative review of data in Australia with respect to the current influenza vaccine effectiveness against the H3N2 influenza A virus. As I wrote late in 2017, that the Australian government estimated that the actual effectiveness ranged from 16-33% effective against hospitalization from the flu, so that seems to be much higher than what was stated in the Eurosurveillance article.

In addition, the 10% figure is for only the H3N2 antigen in the vaccine – it still is effective against the influenza A H1N1, and two influenza B viruses. But in the end, I said that almost all predictions about the influenza vaccine effectiveness were estimates based on rather limited data. But now we have better information after a few months of the season, and the CDC just published the data in a peer-reviewed journal. Let’s review real data instead of estimates.

Influenza vaccine effectiveness estimates

The article, published in Morbidity and Mortality Weekly Report, takes a detailed look at at the influenza vaccine effectiveness. The study tracked 4,562 outpatients in Michigan, Pennsylvania, Texas, Washington, and Wisconsin who had acute respiratory illness and cough. They determined whether or not the patients had laboratory-confirmed influenza and vaccination status.

Here are some of the key data points (out of the literally hundred different pieces of data you can dig out of this article) that should help our understanding of the effectiveness of the current flu vaccine:

  • Approximately 50% of the study patients had received this season’s flu vaccine.
  • The overall influenza vaccine effectiveness (combining all four flu viruses in the current quadrivalent vaccine) is approximately 36%.
  • Importantly, because children die of the flu, the overall effectiveness for the 6 months to 8-year-old group was about 59%.
  • The overall effectiveness of the H3N2 variant was about 25%, 2.5X higher than the current tropes about the vaccine.
  • However, the effectiveness against H3N2 for children was about 51%.
  • The total effectiveness against the H1N1 variant was about 67%, and against the influenza B viruses, it was around 42%.

Let me emphasize once more – the overall effectiveness of the vaccine against H3N2 in children was around 51%.

In other words, if you’ve been on the fence about giving your child the flu vaccination because you think it doesn’t work, well please think again. At least half of children who get the vaccine are protected against the H3N2 virus that is causing much of the flu hospitalizations this season.

Think about it – you can protect your child against the flu, against hospitalization against the flu, and against death caused by the flu. And don’t use the argument that somehow your child’s superior genes, diet, and homeopathic potions are going to protect them against the consequences of the flu – healthy, athletic, strong children are dying of the flu.


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The Original Skeptical Raptor
Chief Executive Officer at SkepticalRaptor
Lifetime lover of science, especially biomedical research. Spent years in academics, business development, research, and traveling the world shilling for Big Pharma. I love sports, mostly college basketball and football, hockey, and baseball. I enjoy great food and intelligent conversation. And a delicious morning coffee!