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Concerns raised over Covid-19 human challenge trials

Bioethics council urges researchers and funders to consider ethical implications

The Nuffield Council on Bioethics has raised a number of ethical concerns over plans for human challenge trials in which volunteers would be deliberately infected with Covid-19.

On 20 October, the government announced a £33.6 million investment in human challenge studies in partnership with Imperial College London, study provider hVIVO and the Royal Free London NHS Foundation Trust.

The trials would involve a vaccine candidate being given to a small number of healthy adult volunteers who would then be exposed to the virus in a “safe and controlled environment”, the government said. The volunteers would then be closely monitored to see exactly how the vaccine worked and to identify any side effects.

If approved by regulators and ethics committees, the studies would start in January, with results expected by May 2021.

However, concerns have already been raised about the ethics of such trials, with the Nuffield Council on Bioethics urging those involved in developing the studies or related research proposals to consider the scientific justification.

The council also urged researchers and funders to consult and engage with the wider public from the beginning. “They must make sure that public concerns are properly understood and addressed, and that anxieties based on misconceptions can be avoided,” it said.

Researchers and funders should consider what actions must be taken to minimise risks, the council said, “for example by determining which volunteers are highly unlikely to develop serious disease, how volunteers will be monitored, and ensuring they have access to the best possible care”.

Moreover, the council added, “there are significant challenges in ensuring volunteers thoroughly understand the risks and the uncertainty of any benefit. Volunteers will also be committing to stay within a biosecure facility until they are no longer infectious.”

Several scientists have also raised concerns.

Doug Brown, chief executive of the British Society for Immunology, welcomed the studies but said: “It’s important to remember that no studies of this type are completely free of risk. One aspect that will need to be taken into consideration with Covid-19 is that we don’t currently have many proven treatments to give to people who become very sick with the illness.”

Stephen Griffin, associate professor in the school of medicine at the University of Leeds, also highlighted that “as an effective rescue therapy does not yet exist for Sars-Cov-2, there is a serious ethical dilemma for the Medical and Healthcare Products Regulatory Agency committee to address here”.

He added that given that “we are seeing a worrying resurgence in cases, we must question whether direct challenge studies are necessary as vaccinees are increasingly likely to be exposed to infectious challenge in their natural environment”.

And Jonathan Ball, professor of molecular virology at the University of Nottingham, said that “any studies involving the novel coronavirus will focus on those most likely to experience a mild infection—young healthy volunteers. Yet the people we need to protect against serious disease are more vulnerable elderly people, so what we learn from challenge studies might have limited wider relevance.”