Scientists Developing Coronavirus Strain To Deliberately Infect Volunteers in Human Challenge Trials of COVID-19 Vaccine

US government scientists have begun manufacturing a strain of the novel coronavirus for use in human challenge trials of COVID-19 vaccines, a type of study in which healthy volunteers will be vaccinated and then intentionally infected with the virus, according to a Reuters report.

Vaccine trials generally rely on inadvertent infection, which can take time to occur. Some drugmakers plan to undertake human challenge trials to test their COVID-19 vaccines only if required. However, US officials are under pressure from advocacy groups and others who consider challenge trials as a way of speeding up tests of COVID-19 vaccines. Some scientists also consider human challenge trials of the novel coronavirus as unethical due to the absence of any “rescue therapies” for volunteers who become ill. Such trials are usually conducted when a virus is not circulating widely, which is not the case with COVID-19.

In order to prepare for possible challenge studies of COVID-19 vaccines, the NIAID is making efforts to manufacture a suitable SARS-CoV-2 strain, draft a clinical protocol and identify resources that would be required to conduct challenge studies. The NIAID could conduct small challenge studies in small isolation units to control the virus, while carrying out larger challenge studies involving 100 people or more across multiple locations. A statement emailed to Reuters by the National Institute of Allergy and Infectious Diseases (NIAID Bethesda, MD, USA), part of the National Institutes of Health, stated that the work for conducting challenge trials was still in the preliminary stages, although such trials would not replace the large-scale, Phase 3 trials ongoing in the US for testing experimental COVID-19 vaccines. The NIAID has said that it continued to prioritize field trials to evaluate SARS-CoV-2 vaccine candidates, but remains open to the possibility of challenge trials for future generations of vaccines or treatments.

“Should there be a need for human challenge studies to fully assess candidate vaccines or therapeutics for SARS-CoV-2, NIAID has begun investigations of the technical and ethical considerations of conducting human challenge studies,” the agency statement said.

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National Institute of Allergy and Infectious Diseases (NIAID)