| It's trivial to get volunteers. I'll volunteer. In the US we're around SARS2 spreaders all the time. Every time you spend ~30 minutes walking around in a major retail store chain you're highly likely to be exposed to SARS2. Now do that N times per week like most Americans have been for the past year plus. What am I supposed to be afraid of compared to that? I've had Covid; early into the pandemic. It was quite unpleasant. I'll take my chances at another round with it, especially if the science is quite useful and the experiment is reasonable. There is enormous cowardice in the governmental sphere in much of the world today. Otherwise we would have immediately began pursuing challenge trials with the mRNA vaccines, which took a mere few days to create. It would have been trivial to get thousands of volunteers to rapidly begin testing the vaccines and it would have been trivial to work with the government to stage a large physical space to do so (the army could have provided a significant, isolated location easily), at whatever cost in money and resources were necessary. In the meantime, instead, we probably had well over 100,000 people die just in the US that didn't need to, versus had we accelerated the vaccine testing and deployment. Older people have a high vaccination rate in the US, fortunately; we could have gotten vaccines to them sooner. A generation or two prior, we would have used challenge trials to move faster. But then this is the same country that barely shrugs when 100,000 people die in a single year from overdoses. Of course that same cowardly country isn't going to do challenge trials. |
Challenge trials are fine but were hardly needed when we had unchecked spread of Covid for bog-standard RCTs. The historic speed that the vaccines made it through FDA approval were in large part due to the millions of active infections all over the country and world such that you could see the control vs. experimental groups very easily.