Thread by @federicolois

1/n I find it interesting the poor understanding of risk by medical professionals. Just for the record, I am pro-vaccines, but I am anti-ignorance more. If you have risk from 2 independent events (covid positive and vaccination) the risk gets added.

2/n From probability we know that: P(A or B) = P(A) + P(B) + P(A and B)
For context, what is the probability of dying from COVID-19 or dying from Vaccine Adverse reaction.

3/n Purist would say then that we need to take the conditional probability, so the formula would be:
P(dying | COVID-19 or Vaccine) = P( dying | COVID-19 ) + P( dying | Vaccine ) + P( dying | COVID-19 and Vaccine )

4/n While the latter is interesting for regulators and probably not zero, but for all uses and purposes, you die only once. Let's assume it doesn't happen. P( dying | COVID-19 and Vaccine ) = 0

5/n Now we have 2 independent events that happen in sequence. The interesting thing about risk is that it is calculated as Risk = Probability * Loss. While actuaries would say that Loss has a monetary value, for all uses and purposes to understand my own risk I can assume Loss=1

6/n That leads us into an interesting equation. R(dying | COVID-19 or Vaccine) = P(dying | COVID-19) + P(dying | Vaccine)
If you already had been infected by SARS-Cov-2 your probability for P(dying | Vaccine) is independent but it adds to the probability you had when infected.

7/n Some would say that dying from COVID-19 after vaccination is lower therefore are not independent, and I will say yes, but I am more interested into the other sequence, which is pushing vaccination on already recovered individuals.

8/n Those MDs that are pushing vaccination of individuals that had recovered (like the one telling that to my mother-in-law) without telling that their risk is additive are incurring in malpractice. Informed consent is everything, and you are not abiding to it. This is personal.