The case for human challenge COVID-19 vaccine trials

Peter Singer Isaac Martinez
We should be consistent in our attitudes to risk. In other areas of life, we think it is praiseworthy for people to risk their lives (even in a small way) to save others.
Peter Singer Isaac Martinez

Last month, the vaccine advocacy group 1Day Sooner published an open letter to Francis Collins, director of the US National Institutes of Health, urging regulators to permit and begin to prepare for “human challenge” vaccine trials in order to end the COVID-19 pandemic as soon as possible. In these trials, fully informed volunteers would be injected with potential vaccines (or with a placebo) and then would be “challenged” by being intentionally exposed to SARS-CoV-2, the virus that causes COVID-19.

Later this month, a similar letter will be sent to the heads of government health departments in several countries where COVID-19 vaccine research is being conducted, and to Keva Bain, president of the World Health Assembly, the decision-making body of the World Health Organization.

On the day that the open letter to Collins was released, Adrian Hill, director of the Jenner Institute at the University of Oxford and a signatory, stated that he believes that human challenge trials should be “feasible and informative” in the coming months. The Jenner Institute is among the leaders in seeking to develop a vaccine against SARS-CoV-2, and this is the first announcement from a developer indicating support for human challenge trials.

In May, the WHO Working Group for Guidance on Human Challenge Studies in COVID-19 stated that such trials would be “substantially faster to conduct” than standard field trials, in which researchers must wait for a sufficient number of experimental subjects to be exposed before they can show whether the vaccine works. A delay in obtaining a vaccine could mean hundreds of thousands of additional deaths, months more of lockdowns, higher unemployment, and, in many countries, millions of people without enough to eat.

Fifteen Nobel laureates, more than 50 professional philosophers, and many other prominent intellectuals have signed the letter. The involvement of so many philosophers — including those who often take opposing approaches to ethics and agree on little else — is notable. Not all the issues raised by challenge trials fall within the expertise of scientists. Philosophers, or more specifically bioethicists, study research ethics, a field that includes questions about the moral permissibility of challenge trials. They draw on information provided by scientists for their ethical reflection, discussion, and eventually, judgment.

Higher levels of risk

We cannot speak for all the philosophers who signed the open letter, but in our view fully informed volunteers should be allowed to sign up for a potentially dangerous trial that will reduce the time required to bring an effective vaccine to everyone who could be exposed to SARS-CoV-2.

The alternative is that the virus will continue to impose much higher levels of risk on other people, especially health-care workers, the elderly and those with underlying health conditions that reduce chances of surviving the infection.

We should be consistent in our attitudes to risk. In other areas of life, we think it is praiseworthy for people to risk their lives (even in a small way) to save others.

A kidney donor runs a chance of about one in 3,300 of dying as a result of the donation, yet that risk does not lead us to prohibit kidney donation. A young and healthy challenge trial volunteer’s chance of dying would be less than one in 10,000.

This way of thinking leads many ethicists to conclude that we should not prohibit young and healthy people from volunteering for a challenge trial. On the contrary, we should praise them for risking their safety in order to save others.

It is true that the risks of exposure to COVID-19 are not as well known as the risks of kidney donation. Nevertheless, as long as the volunteers understand this uncertainty, many ethicists have decided that the risks are acceptable.

Peter Singer is a professor of bioethics at Princeton University. Isaac Martinez, a 2020 graduate of Princeton University, is a challenge trial volunteer and project manager at 1Day Sooner. Copyright: Project Syndicate, 2020.

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