Originally Posted by
Nephrology
To my knowledge that is not something that they announced specifically. If you have a link to an official announcement along those lines that I would be curious. However, broadly speaking, this is true of all new drugs/treatments/etc etc.
The development of the vaccines proceeded along an accelerated version of the the standard clinical trials timeline in which 3 trials were conducted back to back - the first, a small study in healthy volunteers to demonstrate safety (phase I), then a 2nd that is larger to demonstrate preliminary evidence of success and confirm safety (phase II), and the final (phase III) to confirm efficacy and safety in a large population statistically powered for this goal.
What is true, however, is that the results of the phase 3 trials suggested the vaccines were far more effective than they ultimately proved to be. There are a few factors that likely contributed :
1. The early trials only included healthy 18-65 year olds and did not include immunocompromised patients. We know now fairly decisively that the immunocompromised do not respond as well to the vaccine the otherwise healthy. If they had included the immunocompromised in early studies they likely would have been shown to be less effective. The reason they did this is in part by including the immunocompromised it would introduce an additional variable in their test population which could have statistically diluted the effect of the vaccine. To compensate for this they would need to have enrolled more people which may have potentially delayed rollout of the vaccine. This is a relatively common practice in clinical trials (i.e. developing 'exclusion/inclusion criteria') to focus a question in a way that makes it statistically feasible to get an answer. The pros and cons of this are a nuanced discussion.
2. The early trials of the vaccines only measured effectiveness out to 4 months (120 days). We now know that the immunologic protection from these vaccines in the context of the current prevalence of disease (vaccine effectiveness directly depends on your odds of encountering the disease in the community among other things) wanes at approximately the 6 month mark in healthy people. So the initial 4 month assessment would not have been detected by the initial trials that were the basis of its EUA.
3. By law, physicians cannot prescribe new drugs that have not been proven to be safe/effective. this is a catch-22, of course, because to demonstrate something is safe/effective it has to be used on people. Lab rats do not suffice. For this reason, every drug/device that is trialed in the FDA clinical trials process is evaluated only in a relatively small number of people (on the order of thousands) who sign waivers agreeing to participate in the trial before a given drug approved for use. In the case of the COVID mRNA vaccines, they enrolled 40,000 people between treatment/placebo groups. However, 40,000 is not the same thing as 280 million. There is always the possibility that, as we saw in the COVID vaccines, the results of a clinical trial will not mirror perfectly the rollout to a population much larger than the trial. For this reason open-label post-market studies are becoming increasingly common in order to detect exactly this discrepancy.
Again not familiar with the announcement you're referring to but the spirit of that message is not wrong, for the reasons listed above. The history of medicine is littered with things that we once thought worked that are now relegated to the trashbin of history (eg thalidomide, Xigris...). This does not reflect of a failure of the scientific process but rather a success - if a very messy one. If we did not constantly attempt to re-iterate, re-investigate, challenge dogmatic assumptions, we would be doing a grave disservice to our patients and to society at large.
Let me know I can clarify any of the above.
Which concerns are you referring to? Waning vaccine efficacy?