There are currently numerous debates over whether or not people who have recovered from COVID-19 develop immunity to the disease. By the standards of the the scientific community, what kind of proof would serve to definitively resolve the immunity question one way or another? Additionally, was such proof ever acquired for any other diseases that we've faced?
Definitive proof would be by challenge by live virus as might have to be done with possible vaccine trials
As a result, some scientists have proposed a way to speed up the process – by deliberately exposing volunteers to the virus to determine a vaccine’s efficacy. “This approach is not without risks but has the potential to expedite candidate vaccine testing by many months,” says Nir Eyal, a professor of bioethics at Rutgers University.
Volunteers would have to be young and healthy, he stresses: “Their health would also be closely monitored, and they would have access to intensive care and any available medicines.” The result could be a vaccine that would save millions of lives by being ready for use in a much shorter time than one that went through standard phase three trials.
But deliberately infecting people – in particular volunteers who would be given a placebo vaccine as part of the trial – is controversial. “This will have to be thought through very carefully,” says Prof Adam Finn of Bristol University. “Young people might jump at the opportunity to join such a trial but this is a virus that does kill the odd young person. We don’t know why yet. However, phase-three trials are still some way off, so we have time to consider the idea carefully.”
One would hope that they had immune sera and other facilities available if the trials go badly, and that might happen considering the virus can rapidly mutate so immunity to one strain might not at all protect against another.