Fifteen Nobel laureates are among the prominent scientists calling on the UK government to support trials in which healthy volunteers are deliberately infected with Covid-19 to accelerate vaccine development.
Writing in an open letter to the health secretary, Matt Hancock, the experts said the benefits of “human challenge trials” far outweighed the risks, in line with World Health Organization guidance that has concluded such trials are ethical as long as volunteers are young and healthy, informed consent is procured, high-quality medical care is on hand, and thorough ethical and scientific review is championed.
After an appropriate strain and dose of the virus is selected, vaccinated volunteers are intentionally infected – yielding results potentially quicker than conventional vaccine field trials in which researchers must wait for participants to get infected in the real world. These studies can also be used to compare the safety and effectiveness of multiple vaccine candidates.
Human challenge studies have long been successfully employed, dating back to the end of the 18th century, when the English physician Edward Jenner inoculated a young boy with cowpox virus and then exposed him to smallpox as part of an effort that led to the world’s first vaccine. Since then, the method has also been used to develop vaccines for typhoid, cholera and malaria. But some scientists have reservations about exposing volunteers to a virus for which there is no cure.
The mortality risk of Covid-19 in healthy (and unhealthy) 20 to 29-year-olds is lower than that of living kidney donors, which is a relatively common procedure, the letter signed by 178 scientists and academics highlighted.
In the case of kidney donation, the volunteer helps one person, noted signatory Dr Nir Eyal, professor of bioethics at Rutgers University.
“But if [human] challenge trials … can help us shorten the pandemic by even one day, not to say several months, they could save thousands and thousands of lives from death, from severe morbidities, and from financial ruin.”
UK government-funded human challenge studies could kick off in January, the Financial Times reported in September, citing sources.
The US and the UK both have experience conducting these challenge trials, noted Abie Rohrig, director of communications at 1Day Sooner, a non-profit organisation that advocates for Covid-19 challenge trial volunteers and published the letter.
“I think the … UK is way ahead of the US in terms of preparing for challenge trials and so we thought it fitting to send a letter to Hancock,” he said.
More than 2,500 UK volunteers have signed up to the 1Day Sooner movement, which has been petitioning parliament to support human challenge trials and fund a challenge study centre to quarantine between 100 to 200 volunteers. Globally, the organisation has attracted over 38,500 willing participants.
“It’s very understandable if a government feels uncomfortable with the idea of a trial in which volunteers are exposed to a virus that that’s potentially deadly,” Rohrig said.
“But we want to signal along with our volunteers that … people from epidemiology, biology backgrounds, as well as psychologists and philosophers think challenge trials could be ethical.”
These studies could also prove valuable when public health measures invariably reduce transmission in the developed world, pushing vaccine developers to shift trial sites to the developing world.
“I think challenge trials are an alternative to simply shipping a trial to a developing country where the virus happens to be raging more — inevitably lower-income countries will have a harder time containing the virus because the trade-offs of economic lockdowns are greater,” Rohrig said.
“The idea that the only back-up in the first world is to presumptuously go to the developing world country has a dimension of post-colonialism, and I think challenge trials are one way of avoiding that, while also respecting the agency of volunteers.”