Scientists are preparing to launch a clinical trial designed to test a Zika vaccine by infecting study participants with the virus—but ethicists are renewing concerns about the trial's potential risks, Emily Baumgaertner reports for the New York Times.
About human-challenge trials
Trials in which human participants are infected with an illness are called human-challenge trials. Researchers have used such studies in the past to evaluate treatments or vaccines for viruses such as dengue, influenza, malaria, and norovirus. In the United States, researchers can only conduct human-challenge trials at a few institutions, according to Baumgaertner.
The Zika trial is backed by NIH funding and aims to evaluate the effectiveness of the potential vaccine by injecting participants with small doses of the Zika virus. According to Baumgaertner, a human-challenge trial might be the only way for researchers to develop a vaccine for Zika, as natural outbreaks have become less common. The researchers behind the trial have said such research is needed to prevent an epidemic in the future.
However, bioethicists on a government panel convened by NIH in 2017 said the trial would have "insufficient value" to warrant the risks—such as unspecified consequences for the study participants and the possible infection of their sexual partners. In the wake of the comments, NIH has not yet determined whether the human-challenge trial will progress.
Panel challenges study design
The bioethicists spoke out again this month in an article published in Science, calling for an ethics committee to review the trial's design before it can move forward.
Seema Shah—a bioethicist at the University of Washington, who chaired the panel and who is a co-author of the new paper—said, "There is no way to turn back time." She added, "When you're asking someone to take a risk that won't benefit [him or her] but may benefit others in the future, you need to know two things—that proper protections are in place, and that it's really going to move the needle."
Researchers challenge the panel's concerns
However, the researchers behind the trial are pushing back against the criticism, saying the panel has raised hypothetical concerns without taking into account the proposed protocol for the research.
In particular, the researchers note that the proposed protocol calls for injecting study participants with minimal doses of the Zika virus and quarantining the participants in a hospital inpatient unit. In addition, the researchers would begin the trial by only enrolling women, who are less likely than men to transmit the Zika virus through sex, and the researchers would require women to use long-term birth control.
Anna Durbin, a research clinician at Johns Hopkins University who was involved in developing the study's design, said, "This ethics consultation was debilitating for the whole community. It really slammed the door on progress."
Stephen Whitehead, an NIH vaccine researcher, called the panel's concerns "really insulting." Whitehead said, "We've been painted as mad scientists who do horrible studies on human beings. But we're on top of all these risks" (Baumgaertner, New York Times, 4/20).
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