You'd ask. I recall seeing multiple human interest stories about people who were eager to volunteer for challenge trials. I believe challenge trials are how the

You'd ask. I recall seeing multiple human interest stories about people who were eager to volunteer for challenge trials. I believe challenge trials are how the original vaccines were tested in the earlier 20th century prior to contemporary developments in medical ethics. And you'll get volunteers. It's a rational decision for effective altruism. Say you face a 1% chance of death but a 50% chance of substantially contributing to saving a million lives. If that's technically possible, highly informed people should have the opportunity to make that choice. I believe some of the earliest challenge testers were the developers of the drug themselves.