3 ms·
Safety is the primary purpose of P2, but the size of those trials is often still too small (often 100 to 500) to detect rarer toxicity events, especially in sec
by randcraw 6y ago
Safety is the primary purpose of P2, but the size of those trials is often still too small (often 100 to 500) to detect rarer toxicity events, especially in secondary groups often excluded (e.g. juveniles) in trials that initially target a different primary group (e.g. old folks) for approval.
Many drugs fail due to toxicity only during/after P3 when the number of subjects (often 1000 to 30,000) is sufficient to engage sufficient contraindication factors and power needed statistics to reveal detail in the edge cases.
- marcosdumay 6y agoWhat is a reasonable prior for the toxicity of an old tech vaccine (like viral vector, that is reasonably common for COVID) that passed P2? We have been making vaccines for a while, we should be able to answer that. Also, how long do we need to wait on P3 before we get the toxicity result? A really rigorous answer is that we need several years because some problems appear very slowly. Yet, we are not waiting those years. We are declaring definitive success with incomplete information. What is very reasonable, because it is very unlikely that those vaccines will have long term toxicity... but then, why are we using that prior, but refuse to use the P2 or early P3 results to make a temporary decision? Why we decided that it was ok to try the vaccine on 10s of thousands in June, but couldn't expand that number to 100's of thousands on July, or millions by August? The decisions were taken by calgo culting regulations, and caused a lot unnecessary harm.