During the onset of this current global health crisis, tens of thousands of young volunteer participants offered to risk their health by allowing scientists to intentionally infect them with SARS-CoV-2, with the hope of accelerating the hunt for an effective cure or vaccine.
Various study groups announced plans to try these so-called "human challenge tests," even as some scientists doubted whether they could be done in an ethical manner.
Now with the recent news that COVID-19 human trials have produced at least two very promising vaccines, researchers are arguing whether planned challenge tests are still needed. Specifically, in the United States, one budding initiative seems to be on hold.
However, in the United Kingdom, scientists say they are moving forward. According to London-based Imperial College immunologist and lead research for the proposed UK trial, Christopher Chiu, there are still "many strong arguments" for pushing through with human challenge tests.
Deliberate Exposure to the Virus, Prevalent with Ethical Concerns
In customary human trials, scientists provide volunteers with either a vaccine or placebo, then wait for a couple of months or longer for enough circumstances to occur so they can gather statistically rigorous results.
Reports on this recent news say challenge trials "can move faster by first vaccinating volunteers" and then exposing them deliberately to SARS-CoV-2 "in a controlled setting."
Following intentional exposure to the virus, scientists would then closely follow the volunteers for days or even weeks. The challenge trials, though, are also prevalent with ethical concerns.
For instance, since no reliable cures for severe cases of COVID-19 have taken place, volunteers who agree to test a vaccine could be putting their lives at risk if they fall ill.
Careful Approach Adopted
Medical authorities all over the world have implemented a careful approach. Even one year after the pandemic started, not such a trial is said to be underway.
In relation to this report, supporters say, challenge trials could still "advance science and save lives." They add, these tests could be applied to compare the efficacy of different vaccines, for example, and help rapidly screen "the most promising second-generation candidates" from the dozens currently now in the works.
In addition, challenge trials could provide an answer to the unknowns, too, like what immunological markers specify an individual is shielded from COVID-19, and whether vaccines are, indeed, blocking the entirety of the infection or just simply preventing people from falling ill.
This, experts say, is essential because, if a vaccinated individual can still spread the virus, people who did not get the vaccine would be at risk.
Promises Efficacy
Chiu, commenting on the reports on the issue, said, is comfortable with deliberately infecting people with SARS-CoV-2 as there is increasing evidence that young adult individuals "have a low risk of serious illness."
To prove efficacy, he consulted with King's College London researchers who helped manage an app that tracks COVID-19 symptoms for over four million individuals.
Out of 650 young adults who had confirmed cases of the virus, nine in 10 did not show symptoms after three weeks, while symptoms of "a few 'outliers' resolved a few months later, explained Chiu.
In the US, though, the recent vaccine results put a hindrance on eagerness for human challenge tests. A month ago, Matthew Memoli, a virologist, put the final touches on plans for a challenge trial at the NIAID or the National Institute of Allergy and Infectious Diseases. He is the head of the Clinical Studies Unit at the Laboratory of Infectious Diseases. To date, he reveals, the project "is in limbo."
After the first news about the success of vaccines, reports said Memoli heard Anthony Fauci, Director of NIAID, as well as Francis Collins, the National Institute of Health head, making remarks at an online discussion with the Bill & Melinda Gates Foundation, proposing that the challenge experiment "might not be necessary." Collins verified the exchange via a spokesperson.
A Welcoming News
Reports about the online meeting said, is "welcome news to some," who are afraid that challenge trials exhibit risks of severe complications and caution that the lingering impacts of COVID-19 infections are uncertain.
Infectious disease expert Wilbur Chen, from the University of Maryland, Baltimore, who has done several challenge trials to research intestinal diseases like cholera, for one, says such tests are far more dangerous for COVID-19.
Chen continued, antibiotics could effectively provide treatment to his volunteers if they fell ill. However, he explained, "I don't think there's a good rescue therapy right now" for this new coronavirus.
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