Monday, March 9, 2020

Seasonal flu vaccine effectiveness and survivor-bias

Suppose you bet on track events. Furthermore, suppose your favorite event is the 110m hurdles.

The reason you LOVE the 110m hurdles is because you are magic and have the ability to place invisible, five pound weights on the left ankle of any three runners while they still have three hurdles left in the race.

Suppose that in a moment of weakness you reveal your magic to somebody who is not a track fan nor is very smart about statistics.

"So, who did you put the weights on during the last race?" the dummy asked.

You mention that you placed them on the three front-runners who were not your bet.

The dummy looks at the finish-heat sheet and will say "You picked the wrong ones to handicap. They didn't come anywhere close to winning."

"Huh?!? Wasn't that the whole point?" you ask.

"No. You wasted your magic. Clearly those runners didn't need to be handicapped because they didn't finish first, second, third." the dummy persists.

We see the media acting like the dummy every season with regards to the seasonal flu vaccine.

Headlines read something like "The CDC screwed up again. Seasonal flu vaccine only 33% effective against flu strains currently circulating."

Using flu to 'frame' Covid-19
People crave a frame-of-reference with the Covid-19 virus that is ramping up. The obvious baseline is the seasonal flu. Aesop did a good job here.

Then, once they are shown the comparisons they argue to protect their state of denial.

One argument you might hear is "Well, the flu vaccine never helps anyway."

That dismissal of the flu vaccine suggests the person subcontracted their critical thinking out to the mainstream media and shows a lack of understanding about the survival-bias.

The fact that the strains that were included in the vaccine are not the dominant strains at the end of the season suggests that the vaccine did a sterling job on the three-or-four strains that were included. They fizzled and the other strains floating in the background hit the finish-line first.


  1. Yep, prediction is impossible to know a year ahead. You take your best shot and hope for the best.

  2. Like the WW II aircraft repair crews reinforcing shot-up areas on the aircraft that made it back.

    Those places didn't need reinforcing. The airplane made it back without.

    It was other places that needed improvement.


Readers who are willing to comment make this a better blog. Civil dialog is a valuable thing.