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We run trials of vaccines to learn about (at least) two things: does the vaccine offer a protective effect and how safe is it. But we don’t just care about safety at time of injection because adverse events can take time to materialize. https://www.nytimes.com/2020/12/02/health/covid-vaccine-placebo-group.html
We have had good news about 2 vaccines. But it’s important for those trials to run to completion. Without a placebo comparator, it is much more difficult to know if adverse events are part of the background conditions of normal life or due to the vaccine.
But if the vaccines work, how can we run those rials to completion? For one, there are going to be millions of people we can’t vaccinate for months or years. During that time it is reasonable and permissible to continue the trial. Can participants withdraw? Yes, at any time.
Am I saying that we don’t have a special obligation to people in these trials. No. I think we do have such an obligation. Members of the placebo arm should be among the first in line when the trial ends.
But there is no obligation to vaccinate the control group as soon as we have an estimate of efficacy and doing so deprives patients, clinicians, and policy makers of valuable information regarding the net prophylactic merits of the vaccine.
Am I saying we should force members of the control group to stay in the trial? Nope. I’m saying that we need to make the value of continuing the trial clear to participants and ask them to stay in. They are free to withdraw at any time.
Remember that vaccines are given to healthy people. Healthy people will care about the possibility of adverse events. This information isn’t irrelevant, especially since part of the social value of vaccines is conditional on widespread use.
One last thing, two of these vaccines are not just the first vaccine for a novel infect, they are the first to use a novel RNA mechanism. Reducing uncertainty around this novel platform has considerable value, but that s difficult to do without a comparator.
Ok, one more thing. While the vaccine is rolling out, we are asking some people to wait to get the vaccine so that others can go first—health care professionals etc. if it’s ok to ask some people to wait, it has to be acceptable to ask trial participants to wait. Moreover...
The best time to ask this is during informed consent.
