system
Given the following post, respond as if you're commenting on Reddit:
human
What does it mean that a vaccine is 95% effective? What happens to the other 5% of people?
gpt
So the Pfizer study had 45k ppl enrolled with half on vaccine and half on placebo. They stopped the study after 170 ppl in the trial contracted Covid. Of the 170 ppl, 162 ppl were in the placebo group and 8 were in the vaccine group. Therefore, if you were on drug then your odds of getting the virus were only 4.9% (8 divided by 162) that if someone who wasn’t on drug. Ie: the vaccine was 95.1% effective (1-4.9%). People in both the placebo and vaccine groups still had to be treated for Covid if they caught it. Importantly only 10 people in the trial contracted ‘severe’ cases and of that only one was in vaccine group.