U.S. scientists making coronavirus strain for potential human challenge trials

U.S. scientists are manufacturing a strain of the novel coronavirus that could be used to test the efficacy of COVID-19 vaccines on humans.

So-called challenge trials are controversial because they intentionally expose people to a pathogen without having a proven vaccine. But they typically are only used when a pathogen is not circulating widely – unlike the coronavirus.

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The manufacturing work being conducted by the National Institute of Allergy and Infectious Diseases is only at the preliminary stages, Reuters reported Friday. Any challenge trials would be intended to supplement large-scale trials currently underway in the U.S. 

The advantage of challenge trials is that they could speed up vaccine testing as most studies rely on inadvertent infection. 

Drugmakers like AstraZeneca and Johnson & Johnson told Reuters they would consider using challenge trials to develop COVID-19 vaccines if necessary.

Any small challenge trial, which could take months to establish, would take place in small isolation units to prevent an outbreak of the virus, the NIAID told Reuters. Larger studies, involving about 100 people at multiple sites, would follow. But this would take months. 

More than 33,000 people from 151 countries have volunteered to participate in challenge trials, according to the advocacy organization 1 Day Sooner.

More than 759,000 people have died of COVID-19, including 167,000 in the United States.