Experts seek approval for COVID-19 trials

"The more successful the pandemic containment measures are, the harder it is to test vaccines by conventional field trials, so challenge studies need to be considered," Andrew Catchpole, chief scientist at hVIVO, told China Daily.

Anna Durbin, a professor of international health at the Johns Hopkins Bloomberg School of Public Health, is a proponent of the human challenge method, though she said that as things stand, COVID-19 challenge studies have an "extremely high degree of risk".

"Not only to participants but also to staff and, potentially, to third parties," Durbin told China Daily. "There is a tremendous amount we do not know about this virus and although younger people are less likely to get severe disease, we still see severe disease in young people."

Durbin has run a number of challenge trials on other illnesses, and is on a World Health Organization committee that will publish guidance for COVID-19 human challenge studies within the next couple of weeks. Durbin's opinions here are her own and do not necessarily reflect those of the WHO committee.

Meanwhile, many medical experts remain convinced that challenge trials for COVID-19 are justified, given how quickly they could accelerate the route to an effective vaccine. A cohort of researchers, including scientists from Harvard, Oxford, and Johns Hopkins universities, recently formed an initiative called 1 Day Sooner to recruit volunteers to prospective challenge studies. More than 28,000 people from around 100 countries have signed up so far. The group estimates that speeding up vaccine development by just three months could save more than half a million lives.

Catchpole, hVIVO scientist, said that challenge studies have the "potential to be transformational "in fast-tracking decision-making in the loaded field of COVID-19 vaccine candidates, of which there are more than 120.

Christopher Chiu, an infectious disease specialist at Imperial College London, said he is cautious about the use of the challenge method for COVID-19 as there is not enough known about the long-term consequences of infection.

"However, it is clear that there is a demand for challenge studies to test the efficacy of vaccines, and by accelerating vaccine development there could be a huge positive impact on global health," Chiu told China Daily.

hVIVO has conducted 50 previous viral challenge studies in the last two decades, and Open Orphan head Friel said he is confident that the lab will gain approval from UK authorities.

Friel estimates that around 20 COVID-19 vaccines are "in a serious stage of development", and hVIVO is in "active discussions" with several of these companies about running studies.

hVIVO hopes to commence challenge trials later this year, at which point companies would know if their vaccines are effective "within weeks". Even so, further compulsory safety studies would take a year or more before vaccination programs expand from frontline workers and vulnerable people to the wider population.