- Researchers have said that a coronavirus vaccine could be reached sooner if human challenge trials were allowed. Doing so would help speed up vaccine efforts by a few months.
- The FDA, however, has never allowed human challenge trials to take place without a cure or adequate treatment available.
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Without a coronavirus vaccine, there’s a good chance that we won’t be able to return to a pre-coronavirus lifestyle for quite some time. Even if the coronavirus subsides in the coming weeks and months, there’s a very real fear that a second and more dangerous wave will spring up later this year. Earlier this month, a report from the Center for Infectious Disease Research and Policy at the University of Minnesota said that the coronavirus pandemic could last for as long as two years without a proper vaccine.
Coming up with a coronavirus vaccine is certainly challenging, but developing a vaccine in a compressed time frame adds an entirely new layer of complexity. As a result, there has been talk — mostly theoretical — about accelerating the testing process and introducing human trials of a potential vaccine sooner than what would ordinarily be allowed.
Typically, a potential vaccine is tested on animals first which is then followed by testing on a small group of humans. If that test proves promising, testing on a larger group of humans begins. That is then followed by Phase 3, which takes the longest amount of time.
This normally evaluates the effectiveness of the vaccine in a study involving thousands of participants, and is the final step before a vaccine is deemed safe enough for regulators to allow widespread use. To show that it is both effective and safe, researchers look at differences in infection risks and side effects between those who receive the vaccine and those given a placebo. The hope is to find a vaccine that both reduces the chances of infection, and causes no (severe) side-effects.
Because this can be quite a long process, a March paper from the National Center for Biotechnology Information argues that we can speed up the process by a few months by infecting volunteers with potential vaccines in a controlled setting:
Controlled human challenge trials of SARS-CoV-2 vaccine candidates could accelerate the testing and potential rollout of efficacious vaccines. By replacing conventional Phase 3 testing of vaccine candidates, such trials may subtract many months from the licensure process, making efficacious vaccines available more quickly.
This strategy, of course, would be risky:
Obviously, challenging volunteers with this live virus risks inducing severe disease and possibly even death. However, we argue that such studies, by accelerating vaccine evaluation, could reduce the global burden of coronavirus-related mortality and morbidity. Volunteers in such studies could autonomously authorize the risks to themselves, and their net risk could be acceptable if participants comprise healthy young adults, who are at relatively low risk of serious disease following natural infection, they have a high baseline risk of natural infection, and during the trial they receive frequent monitoring and, following any infection, the best available care.
This all begs the question: would a sufficient number of humans even volunteer for such testing? The answer to that question, perhaps surprisingly, is a resounding yes. Per 1DaySooner, more than 16,000 people have already expressed interest in signing up for a “human challenge trial for COVID-19 if one were to occur.”
All that said, it’s unclear how many people who indicated an interest in volunteering themselves would actually follow through. What’s more, the FDA has never authorized “human challenge trials especially if there is no immediate cure available.”