COVID-19 challenge trials: is there a compelling ethical argument against?

Daniel Hausman, a research professor at Rutgers Center for Population-Level Bioethics and author of a new paper, published in the Journal of Medicine & Philosophy, discusses his findings surrounding the ethical issues of human challenge trials.

In human challenge trials, healthy volunteers are given a treatment/vaccine or a placebo and then intentionally exposed to a pathogen/harmful agent to test the effectiveness of the therapy. Some are scheduled to begin testing COVID-19 vaccines and treatments in the UK in January 2021. However, since they were announced, these trials have sparked ethical debates around the benefits of developing a vaccine quickly versus the risks of directly exposing people to coronavirus.

What are the benefits and risks of challenge trials?

“Since researchers do not have to wait for participants to be exposed to the virus naturally, some suggest challenge trials will save considerable time and thousands of lives in the midst of the pandemic. By selecting only a small number of young and healthy volunteers, the risk that any would be hospitalised would be very low – and the risk of permanent injury or death lower still.

“One might think that the possibility that challenge trials would save thousands of lives could easily justify subjecting well-informed volunteers to these risks. However, some ethicists and some members of the public still have qualms. It is these that I try to understand and respond to,” explained Hausman

What are the ethical concerns around challenge trials?

Hausman said there were three main arguments:

1. That researchers ought not to expose healthy volunteers to more than minimal risks, unless the research has therapeutic value for the volunteers;
2. that it is never morally permissible to intentionally harm innocent people; and
3. how much risk experiments can impose on the whole group of participants, even if the risk to individuals is small.

He dismissed the first argument by saying that if this rule were taken seriously, “it would rule out most research” because the participants in the control arm receive no treatment. Instead, he suggests: “while there must be an expected benefit to justify imposing risks on participants, the benefit does not need to be for participants themselves”.

The second he said is mistaken, as it would also prohibit many other medical practices, such as kidney or liver transplants from live donors, which intentionally impose harm on the donors.

He said the last is a judgement call, “but given the potential benefits from human challenge trials, I would call it in their favour”.

How compelling are the concerns?

“I looked for a compelling ethical objection to challenge trials for COVID-19 vaccines but found none – assuming they have the huge benefits and low risks that have been claimed,” concluded Hausman.