US to manufacture virus for human challenge tests


U.S. government scientists have started efforts to make a strain of COVID-19 that could be used in human vaccine challenge trials, a controversial type of study in which healthy volunteers are vaccinated and then intentionally infected with the virus, Reuters learned.The work is preliminary and such trials would not replace large-scale Phase 3 trials such as those currently underway in the United States to test Moderna and Pfizer’s investigational COVID-19 vaccines, according to an emailed statement to Reuters by the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health.

U.S. officials organizing the fight against the pandemic have come under pressure from advocacy groups such as 1 Day Sooner and others who see provocation trials as a way to speed up testing of a COVID-19 vaccine. Most vaccine trials rely on inadvertent infection, which can take a long time to occur.

Some drugmakers, including AstraZeneca and Johnson & Johnson, have said they will consider human challenge trials to test COVID-19 vaccines if needed.

“If human challenge studies were to be required to fully evaluate candidate vaccines or therapies against SARS-CoV-2, NIAID has begun investigations into the technical and ethical considerations of conducting human challenge studies,” indicates the agency.

This includes efforts to make an appropriate strain of SARS-CoV-2, write a clinical protocol, and identify the resources that would be required to conduct such studies.

Small challenge studies would be done in small isolation units to control the virus. Larger challenge studies involving a hundred people are expected to be carried out in multiple locations, adding months of preparation to coordinate the studies.

Such tests are usually done when a virus is not circulating widely, which is not the case with COVID-19. Many scientists consider human provocation tests for COVID-19 to be unethical because there are no “rescue therapies” for those who fall ill.

Earlier this week, Johan Van Hoof, global head of vaccines for J&J, said in an interview with Reuters that preparations for the trials were underway around the world and the company was monitoring those preparations.


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