Get A New Covid Shot? The Evidence Suggests Otherwise

Taking a new Covid shot every winter has no empirical basis. The burden of proving effectiveness against death squarely rests on public health officials and anything short of a double-blind, placebo-controlled randomized trial is unacceptable. And that applies to the flu shot as well.

The healthy vaccinee bias, which many mistakenly call selection bias, is a type of confounding bias.

There was only moderate healthy vaccinee bias in ages 60-79 and no bias at all in ages 80+. What kind of healthy vaccinee bias was accounted for? Why do we observe a bias factor of 1? Following correction, the booster effectiveness in ages 80+ was somewhat higher, not lower, than in ages 60-79.

Data from Israel A letter to the editor of the New England Journal of Medicine has recently generated considerable interest in the healthy vaccinee bias.

Rather than correcting the bias using counts, rates, or age-adjusted rates, it is also possible to correct the bias by a two-step procedure.

We may assume that physicians are more reluctant to attribute death to Covid in a vaccinated patient than in an unvaccinated patient "Because the vaccines are highly effective." Still, they do record Covid as a cause of death in vaccinated patients, but they might do so differently for patient A versus patient B. The Covid death of patient B, who is "Up to date" on vaccination status, is more likely to be mistakenly recorded as non-Covid than the Covid death of patient A who is not.

Suppose 5 percent of 491 non-Covid deaths in ages 60-79 were actually Covid deaths, which were misclassified Nonetheless, there was differential misclassification as explained above: 6 percent of 239 non-Covid deaths in three-dose recipients were Covid deaths, whereas only 4 percent of 252 non-Covid deaths in two-dose recipients were Covid deaths.

After correcting for both differential misclassification bias and the healthy vaccinee bias, we get only 28 percent effectiveness of the third dose. 

https://brownstone.org/articles/get-a-new-covid-shot-the-evidence-suggests-otherwise/