Tag: Vinay Prasad

Observational studies of COVID vaccine efficacy are riddled with bias/ Not counting cases 14 days after dose 2 is a problem

Mary Pat Campbell

Link:https://www.drvinayprasad.com/p/observational-studies-of-covid-vaccine

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In the experiment, he says, what if we compare the control arm of the Pfizer study against an imaginary vaccine arm. And for the thought experiment assume the vaccine is useless. As the table above shows, both groups have identical numbers of covid cases— just what you would expect from a useless vaccine. A straight forward analysis shows no benefit (second to last row)

But in the ‘fictional vaccine observational study’ cases are excluded for 36 days. When this is done the useless vaccine, looks like it reduces infections by 48%!!

Doshi makes a very good point in his paper that the solution is to subtract the 36 day infection rate from the observational control arm. Sadly most investigations don’t do that.

This is one of several biases Doshi discusses, and it plagues the vaccine literature.

Author(s): Vinay Prasad

Publication Date: 14 May 2024

Publication Site: Vinay Prasad’s Observations and Thoughts, substack

Unhelpful, inflammatory Jama Network Open paper suggests that people in Red states dream up vaccine injuries

Mary Pat Campbell

Link:https://www.drvinayprasad.com/p/unhelpful-inflammatory-jama-network?utm_source=post-email-title&publication_id=231792&post_id=143191018&utm_campaign=email-post-title&isFreemail=true&r=9bg2k&triedRedirect=true&utm_medium=email

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Now let’s turn to the paper. Here is what the authors find (weak correlation btw voting and vaccine injuries) , and here are the issues.

  1. These data are ecological. It doesn’t prove that republicans themselves are more likely to report vaccine injuries. It would not be difficult to pair voting records with vaccine records at an individual patient level if the authors wished to do it right— another example of research laziness.
  2. What if republicans actually DO have more vaccine injuries? The authors try to correct for the fact by adjusting for influenza adverse events.

Let me explain why this is a poor choice. The factors that predict whether someone has an adverse event to influenza vaccine may not be the same as those that predict adverse events from covid shots. It could be that there are actually more covid vaccine injuries in one group than another— even though both had equal rates of influenza injuries.

Another way to think of it is, there can be two groups of people and you can balance them by the rate with which they get headaches from drinking wine, but one group can be more likely to get headaches from reading without glasses because more people in that group wear glasses. In other words, states with more republicans might be states with specific co-morbidities that predict COVID vaccine adverse side effects but not influenza vaccine side effects. We already know that COVID vaccine injuries do affect different groups (young men, for e.g.).

Author(s): Vinay Prasad

Publication Date: 2 Apr 2024

Publication Site: Vinay Prasad’s Thoughts and Observations at substack