U.S. scientists are developing a strain of the coronavirus that could be used to deliberately infect volunteers in so-called ‘challenge studies,’ a government agency said Friday.
The work is preliminary and the government will continue to prioritize randomized clinical trials of vaccine candidates, said the National Institute of Allergy and Infectious Diseases (NIAID).
Several of these have entered their final stages, including the faxes developed by Moderna, Pfizer and AstraZeneca.
But NIAID has nevertheless “begun efforts to produce a strain that could be used to develop a human challenge model, if necessary,” it said in a statement.
In normal clinical trials, volunteers receive a medicine like a placebo and their health is then monitored over the course of months of years.
Scientists are looking at how well the vaccine worked as a treatment when the person was naturally exposed to the pathogen.
A faster way to test if a drug works is by deliberately infecting volunteers, as has been done in the past for flu, malaria, typhoid, dengue fever, and cholera.
In the US, advocacy groups such as 1DaySooner support challenging studies for COVID-19, but the topic is controversial because of how serious the disease can be and because its effects are not fully understood.
NIAID said it was likely to reach a decision by the end of 2020, when the late-stage clinical trials that are underway will report their results.
This would help determine if challenge studies are needed, safely and ethically, it added.
David Diemert, director of the research unit for vaccine trials at George Washington University, which oversees a trial of Moderna’s vaccine in the US capital, told AFP that he did not think challenge trials were appropriate for COVID-19. .
“I think they are a critical tool, but only under the right circumstances,” he said.
Diemert even leads a challenge test in a vaccine against a hookworm.
But he said that for COVID-19, “we do not have a very clear understanding of who is at risk of developing serious illness and we do not have a treatment that is guaranteed to cure anyone if they develop a serious illness. “
There is also enough widespread community transmission in the US – the least hit country in the world with 5.3 million confirmed cases – to mean challenge trials are not necessary, he added.
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