4 ms·

I read the method used to measure efficacy: They have tested 44,000 people. 50% got a placebo, 50% got a vaccine. Then has been giving them the freedom to get t

I read the method used to measure efficacy: They have tested 44,000 people. 50% got a placebo, 50% got a vaccine. Then has been giving them the freedom to get the covid. 95% of the 50% who got the vaccine haven't contracted the virus. Correct me if I am wrong. Supposing a random person has a 5-10% chance of contracting the virus (according to average cases/testing worldwide), should the efficacy be 5-10% * 95% = 0.7%-0.5%?

blackrock 6y ago
(A) Did they have someone with Covid-19 sneeze or cough or spit on them? (B) Or did the candidate just go about their daily lives afterwards? Because, unless path A was taken, then this 95% efficacy sounds very misleading.
- mansr 6y ago
  Nothing is misleading. Half the participants got the vaccine, the rest placebo, before going about their usual lives. Now, a few months later, 95 cases have been confirmed across both groups. Of these, 90 had received the placebo and only 5 the vaccine. If the vaccine didn't work at all, the split would be roughly 50/50. A somewhat effective vaccine might result in a 70/30 split, and so on.
  - blackrock 6y ago
    This sounds like a terrible way to test the vaccine’s efficacy. A better test would be to have all the participants walk through a minefield of people with the virus. Breath in all that infected air. Then run the numbers and see who got infected.
    - mansr 6y ago
      It's the standard method, and I see nothing wrong with it. What you suggest (deliberate exposure) is called a challenge trial. This is normally considered ethical only when an effective cure (e.g. antibiotics) is available. Even so, there are plans to conduct such a trial in the UK, and there's no shortage of volunteers. We'll see if they get approval.
dlkf 6y ago
You misread. You write: > 95% of the 50% who got the vaccine haven't contracted the virus. Much more than 95% of the 50% who got the vaccine haven't contracted the virus. They looked at the first 95 people in the entire test to get the virus. Of these 95 people, only 5 were in the treatment group.

blackrock 6y ago

(A) Did they have someone with Covid-19 sneeze or cough or spit on them? (B) Or did the candidate just go about their daily lives afterwards? Because, unless path A was taken, then this 95% efficacy sounds very misleading.

mansr 6y ago
Nothing is misleading. Half the participants got the vaccine, the rest placebo, before going about their usual lives. Now, a few months later, 95 cases have been confirmed across both groups. Of these, 90 had received the placebo and only 5 the vaccine. If the vaccine didn't work at all, the split would be roughly 50/50. A somewhat effective vaccine might result in a 70/30 split, and so on.
- blackrock 6y ago
  This sounds like a terrible way to test the vaccine’s efficacy. A better test would be to have all the participants walk through a minefield of people with the virus. Breath in all that infected air. Then run the numbers and see who got infected.
  - mansr 6y ago
    It's the standard method, and I see nothing wrong with it. What you suggest (deliberate exposure) is called a challenge trial. This is normally considered ethical only when an effective cure (e.g. antibiotics) is available. Even so, there are plans to conduct such a trial in the UK, and there's no shortage of volunteers. We'll see if they get approval.

dlkf 6y ago

You misread. You write: > 95% of the 50% who got the vaccine haven't contracted the virus. Much more than 95% of the 50% who got the vaccine haven't contracted the virus. They looked at the first 95 people in the entire test to get the virus. Of these 95 people, only 5 were in the treatment group.