LONDON — British volunteers will be intentionally infected with Covid-19 as part of an experimental trial that could change scientists’ understanding of the virus.
London is hosting the world’s first coronavirus so-called “challenge trials” in which volunteers are injected with a potential vaccine before being given a nasal-spray dose of the potentially deadly pathogen.
Ahead of the announcement by Open Orphan plc on Tuesday, there has been huge controversy within the scientific community.
Supporters say challenge trials can be far quicker than regular vaccine tests, potentially shortening the wait until the world has access to an effective inoculation.
But critics argue that too little is known about Covid-19 to make challenge trials safe. While young people rarely die of the disease, there is increasing evidence they can be left with long-term debilitating illnesses.
Sue Tansey, a pharmaceutical physician who is a member of the Nuffield Council on Bioethics, an independent British watchdog, said that there was still “disagreement among experts” whether it’s appropriate to go ahead with challenge trials. “People are divided because it’s an ethical conundrum,” she said.
There are more than 150 vaccines in development around the world, a handful of which have reached phase 3 tests, where large numbers of people — as many as tens of thousands — are given the vaccine, while others get a placebo.
In ordinary studies volunteers are sent out into the world and regularly tested for Covid-19 in the hope that there will be some noticeable difference between the vaccinated and non-vaccinated groups. However this can take a long time — many of the participants will take months to get infected if they do at all.
A challenge trial could shorten that timeline: All volunteers get the vaccine, and all of them get the virus too. Researchers say a group of just 40 volunteers would likely tell them a huge amount about any vaccine candidate in just a short space of time. Everyone accepts there are risks.
Sir Patrick Vallance, the U.K.’s chief scientific adviser, said in July that two things needed to happen for challenge trials to be considered safe. Scientists need to know the right dose to administer and to have discovered antiviral drugs that can “rescue” patients who become seriously ill.
Asked what the answers to these questions were, he said, “We don’t yet know.”
Although young people aged 18 to 30 — who typically volunteer for medical trials — rarely die from coronavirus, there is increasing data and anecdotal evidence of young, healthy people crushed by debilitating long-term conditions affecting the heart, brain and lungs.
“The argument against doing it is that we don’t know enough about the cases where some younger people have these long term problems afterwards,” Tansey said. “The other downside is that although we’ve