continuar los ensayos de las vacunas contra la Covid-19
Victoria Parker (C) assesses May Parsons (R) during training at the Covid-19 Vaccination Clinic at University Hospital Coventry in central England, with a protective cover to combat the spread of coronavirus. (Photo by Steve Parsons / POOL / AFP)

The Moderna lab has shared more data on its vaccine’s efficacy. It was revealed in a brief line of the press release that one of the participants, who’d received a placebo, died of Covid-19.

Now that the first vaccines are beginning to be approved, is it ethical to continue clinical trials in which some volunteers don’t receive the treatment? A perspective article published in the Science journal looks at the question.

“When there’s a vaccine or treatment available, it’s more complicated for an agency to accept [doing a clinical trial] because there are ethical problems with giving a placebo. If you can cure or protect a person, why wouldn’t you?” explains Sonia Zúñiga, a scientist at the National Center for Biotechnology (CNB-CSIC), to SINC.

“The more candidates that arrive, the more complicated it is [to carry out this type of study].”

That, at least, is the theory. The debate isn’t new and there’s a lot of literature available on it, but the global health crisis caused by the coronavirus is unprecedented. “This tension between protecting research participants and gathering data that may benefit others is common to clinical research, […] although the present situation is unparalleled,” write the authors of the Science article.

Billions of people —including trial participants who receive a placebo or candidates with no proven efficacy— could benefit from a vaccine against a disease that, until now, has very limited treatments.   However, the article says that challenges such as those associated with the production of these products “highlight the potential value” of conducting additional trials, even though there are already other options. After all, it’ll take multiple vaccines to meet global demand.

“We should continue clinical trials that still have social value and pose acceptable risks,” explains David Wendler, researcher for the National Institutes of Health of the United States and co-author of the article, to SINC. What’s more, he considers it essential to “obtain informed consent” from participants, so that they understand what they’re exposed to.

Value vs. Risk

Wendler defines “social value” as the potential for some trials to provide valuable data, from greater confidence in vaccine estimates to more information on side effects. They will also clear up pending doubts, such as the duration of the vaccine’s protection, its impact on the elderly or on those with multiple medical conditions, and to assess whether the candidate prevents infection.

On the other side of the scale are the risks to which some participants are exposed who could have received a vaccine that’s already considered effective and safe. Wendler explains that this depends on the time during which the placebo is given, the volunteer’s health status, and if they could have accessed a vaccine outside of the clinical trial.

How can we know which way the scales will tip? Which trials can continue and which can’t? Unfortunately, there isn’t an algorithm that can evaluate this. That’s why Wendler considers it “critical” for there to be an independent review carried out by a qualified and independent ethics committee to “assess and confirm that conditions are met.”

“Other clinical trials should be stopped, not started, or redesigned,” he says. As soon as “not a single” study “satisfies the conditions” of having a high social value and acceptable risks, these “should stop.”

Zúñiga, who’s researching one of the Spanish candidates, defends clinical trials continuing. “In the current pandemic situation, with all kinds of patients around the world, I don’t think we’re at that point yet and it’ll be at least a year before we reach it.”

Wendler’s article was written before Moderna announced that one of the participants had died as a result of Covid-19. “I’m concerned that assessment of these clinical trials happens, to a large extent, through press releases,” he laments. “I don’t think it’s the best way to do it.”

Peter Hotez, Baylor School of Medicine researcher and vaccine specialist, wrote a similar criticism on Twitter following the announcement.

“Not sure we want to hear about the death of a study participant from a company press release? Given sensitivities of what this means for continuing placebo-controlled trials, shouldn’t this discussion be led by public health agencies?” Fighting a pandemic is no excuse to leave aside bioethics. (SINC AGENCY / Sergio Ferrer)