Healthy, young people in the U.K. may soon be asked to volunteer to get deliberately exposed to Covid-19 as part of a set of human challenge studies, which aim to speed up the process of vaccine development.
These studies, which are controversial in medical circles, essentially ask volunteers to be "challenged" with an infectious disease organism. The idea behind them is to recruit healthy, young people, inoculate them and then subsequently expose them to the virus to determine if the vaccine is effective. Proponents say such studies can speed up vaccine development, while others say these trials raise ethical questions.
The U.K. government has taken an initial step this week by signing a contract with a pharmaceutical services company called Open Orphan for a so-called characterization study, which involves identifying the most appropriate dose of the virus for use in future human challenge studies. In practice, what that means is the researchers will determine the lowest dose of the virus that would still show up positive on a standard polymerase chain reaction, or PCR, test.
The characterization study is expected to be complete in 2021 and is still subject to ethical and regulatory approval. Sponsored by Imperial College in the U.K., the study will be conducted by Open Orphan's hVivo unit at a London-based research site.
The government has also secured the first three slots to test vaccines using human challenge studies. It's still to be determined whether these studies will move ahead.
"In traditional vaccine trials, all of the subjects get vaccinated and are sent out to live their normal lives," said Andrew Catchpole, the chief scientific officer for hVivo. "But the outcome is that most are not exposed naturally, so you are beholden to how much disease there is spreading in that community."
Catchpole said hVivo already runs more human challenge studies safely for other diseases than any other company globally.
The volunteers participating in the study model must be between 18 and 30 years old, Catchpole said. Their general health will be screened for any risk factors, he said. The study isn't open to pregnant women or nursing mothers.
It remains unclear how many people will raise their hands, but in other countries, such as the U.S., large numbers have already expressed a willingness to participate in such trials.
Medical experts across the globe have mixed views about human challenge studies.
"I think they could accelerate the process and in the midst of a pandemic, so it's worth considering even though they are risky and ethically controversial," said Arthur Caplan, a professor of bioethics at New York University.
Infecting a person with a virus that could have consequences for their health violates the "do no harm rule," Caplan explained.
But the risks can be minimized as much as possible by starting with the youngest, healthiest people who are far less likely to get seriously ill. Participants are typically given antiviral therapies, such as Gilead Sciences' remdesivir, following exposure. It's worth noting, though, that recent studies have questioned the efficacy of these drugs.
Others say that these studies may not be necessary, particularly given the potential harms.
"Given that we may have an approved vaccine in the coming months, I don't know how much challenge studies would speed along the process," said Dr. Jeremy Faust, an emergency medicine physician based in Boston. "There's the possibility here of putting people at risk without much of an upside."
