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The United States government medical research arm is paving the way for Covid-19 “human challenge trials” that would deliberately infect healthy volunteers with coronavirus, as part of efforts to accelerate work on developing a vaccine.
Francis Collins, director of the National Institutes of Health, has asked the NIH vaccine working group to “write a perspective on the scientific and practical considerations for a Covid-19 human challenge model.”
The group, which includes top vaccine developers from universities and industry, will meet on May 11 to discuss the issue.
Challenge trials have a long history in medicine because deliberately infecting volunteers works faster than waiting for them to become infected in the community, but they are inevitably risky.
A growing number of scientists say the world needs a Covid-19 vaccine so urgently that regulators and research funders must make preparations now, allowing human infection studies to begin after potential vaccines have completed their initial safety tests.
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Around 100 Covid-19 vaccines are currently under development worldwide, with several in the early stages of clinical trials.
Volunteers are unlikely to be in short supply: More than 14,000 have already signed up for an online registry run by the US-based vaccine advocacy group 1DaySooner. USA
Political support is also growing. Last month, 35 members of Congress signed a letter written by colleagues Bill Foster and Donna Shalala to the Food and Drug Administration Commissioner and the Secretary of Health and Human Services, urging them to speed up the approval and deployment of a Covid vaccine. -19, including the use of challenge trials.
“We wanted regulators to know that we in Congress understand the justifiable risks involved in human challenge trials,” said Mr. Foster. “They can be essential if we want to classify realistic vaccine candidates to find the one that works best, or as insurance if something goes wrong and the first vaccines don’t work as well as we expect, or if the virus mutates and we need to quickly identify the better alternatives. ”
The pharmaceutical industry would be supportive. Paul Stoffels, chief scientist at Johnson & Johnson, said his company would consider using a human challenge trial for its Covid-19 vaccine to speed up the process, if ethicists accepted the study.
J&J has conducted human challenge trials with other vaccines, including for the common cold, flu, and RSV, a respiratory infection that primarily affects premature babies and the elderly.
But Dr. Stoffels cautioned that deliberately infecting people was “very difficult” without drug or antibody therapy to treat the disease. “If the ethical committees, or the ethical world accepts that it is feasible, we will unite,” he said. “But we don’t have that at the moment.”
Dr. Stoffels added that it would still take several months for people to research how to make and administer the virus and what dose to administer to infect a human.
The FDA said in a statement: “Human challenge studies are one way to accelerate the development of a vaccine to prevent Covid-19. Because these studies involve exposing volunteers to the virus, the studies raise a variety of potential scientific, feasibility, and ethical issues.
“The FDA will work with those who are interested in conducting human challenge trials to help them assess these problems.”
Its regulatory counterpart across the Atlantic, the European Medicines Agency, is also potentially supportive. “Human challenge trials could be very helpful in various parts of the vaccine development process and could provide useful information to regulators,” said Marco Cavaleri, head of vaccine strategy at EMA.
But such studies should provide not only volunteers but also caregivers with the maximum protection against any damage from infection, including possible long-term consequences, said Dr. Cavaleri.
The World Health Organization has just released a 19-page document describing the “key criteria for ethical acceptability of Covid-19 human challenge studies”. Among many other things, he says initial studies should be limited to healthy young adults ages 18-30, with fatal infection rates currently estimated at about 0.03 percent.
Until now, the discussion of Covid-19 human challenge trials “has been fueled almost entirely by the altruism of potential volunteer advocates and the intense considerations of bioethicists,” according to a document prepared for the vaccine working group. NIH. He says the next stage should be preparing the operational and logistical details of a trial.
Practical questions range from how to manage the virus to organizing a secure facility where participants and staff would have to stay for at least four weeks while the trial was conducted.
Then there is the question of which virus to use. The NIH group suggests developing a special “challenge strain” with reduced virulence to administer in challenge trials.
