October 2020 Pulse

The Covid-19 pandemic, which emerged suddenly late last year, is still ravaging many countries in the world, bringing in its wake not only unprecedented disruptions to their economies, but sadly also the loss of many lives.

As I write this article, 5.61 million people have been infected with the coronavirus in America and more than 175,000 have died. In Brazil, there are 3.46 million reported cases of infection and the death toll has climbed to over 110,000.

Countries such as South Korea and New Zealand, which have successfully subdued the spread of the virus, are now reporting a second wave of infections, forcing them to reinstate lockdown measures that have been lifted. Hong Kong and the state of Victoria in Australia are experiencing similar resurgences of Covid cases.

With the escalating number of coronavirus infections across the globe, it is not surprising that scientists are racing against the clock to develop an effective vaccine. While some are sceptical about a vaccine being a silver bullet in combating the virus, many are still convinced that it is one of the most effective solutions to the pandemic.

According to the Wellcome Trust, it usually takes about 10 years to develop a vaccine and at a cost of about US$500 million. But the world cannot wait 10 years for a vaccine for the novel coronavirus.

Currently, more than 100 Covid-19 vaccines are being developed and some have predicted that a couple of them could be ready to go into production globally as early as September or October this year. Dr Jerome Kim, Director-General of the International Vaccine Institute, remarked that the speed with which researchers and pharmaceutical companies have responded to the pandemic is truly unprecedented.

The pressing need for an effective vaccine has led some scientists and researchers to adopt what has been described as the human challenge studies, which they see as a quicker option for vaccine development.

In a provocative paper published in the Journal of Infectious Diseases in March this year, Nir Eyal, the Director of the Centre for Population-Level Bioethics at the Rutgers University in New Brunswick, New Jersey, argues that this method could accelerate the development of a vaccine for Covid-19 and that it can be done safely and ethically.

The human challenge trial involves exposing about 100 young volunteers to the virus to see if those who receive the trial vaccine would escape infection. Eyal is proposing using volunteers between 20 and 45 years of age who are in relatively good health.

Some scientists and ethicists have insisted that it is simply unethical to expose healthy individuals to a lethal virus for which there is no cure.

From the standpoint of Christian bioethics, the safety of participants in a clinical trial is of great importance. While such trials would always involve some risks, no volunteer should be subjected to unreasonable risks, even if informed consent has been properly (i.e., ethically) obtained from them.

This ethical principle is articulated in the Nuremberg Code of 1947, especially in paragraphs 4-6:

  1. The experiment should be so conducted as to avoid all unnecessary physical and mental suffering and injury.
  2. No experiment should be conducted where there is an a priori reason to believe that death or disabling injury will occur …
  3. The degree of risk to be taken should never exceed that determined by the humanitarian importance of the problem to be solved by the experiment.

Eyal has argued that with proper trial design and processes, the risks posed to participants could be kept very low, perhaps even lower than would be the case outside the trial.

He writes:

The low relative risk, that is, the risk as compared to the risk that participants would be facing outside the trial, is part of what makes human challenge studies such a happy marriage of accelerated vaccine testing and ethical treatment of study participants.

In fact, according to Eyal, the risks here are lower than some common surgical procedures and some ethically approved trials. ‘And even the direct risks remain smaller than those of live kidney donation and those of participation in clinical trials that we already find perfectly ethical with volunteers’ informed consent,’ he claims.

Human challenge studies are not new. They have been employed to develop vaccines for arguably less deadly diseases such as typhoid, cholera, malaria and some strands of influenza.

Apart from safety issues, there is also the worry that in the race to develop a vaccine for fame or profit, the human challenge trials would encourage countries with authoritarian governments to conduct the study on vulnerable groups such as prisoners or members of persecuted minorities. Although certain measures can be put in place to address this, such as preventing vaccine makers from selling their products if their trial does not meet acceptable standards, such abuses cannot be entirely prevented.

The World Health Organisation has evaluated the merits of human challenge studies in developing a vaccine for coronavirus and has given its nod of approval. In a paper published on 6 May 2020, WHO presents eight criteria for human SARS-CoV-2 challenge studies, which may be summarised as follows:

  1. Scientific Justification. There must be strong scientific justification for the use of this approach for SARS-CoV-2.
  2. Risks and Benefits Assessment. The potential benefits must outweigh the risks.
  3. Consultation and Engagement. There must be consultation and engagement involving experts and policy-makers as well as the general public.
  4. There should be close coordination between researchers, funders, policy-makers and regulators.
  5. Site Selection. These studies should be ‘situated where the research can be conducted to the highest scientific, clinical and ethical standards.’
  6. Participant Selection. The studies should ensure that participants are carefully selected and that they are exposed to minimum risk.

Given the above considerations and the hitherto unabated spread of coronavirus globally, I am of the view that human challenge studies, although not ethically unproblematic, should be allowed provided proper safeguards are put in place and rigorously implemented or enforced.

I therefore concur with the view expressed by Euzebiusz Jamrozik and Michael J Selgelid in their paper entitled ‘COVID-19 Human Challenge Studies: Ethical Issues’, published in the August issue of The Lancet, that:

… these human challenge studies can reasonably be considered ethically acceptable insofar as such studies are accepted internationally and by the communities in which they are done, can realistically be expected to accelerate or improve vaccine development, have considerable potential to directly benefit participants, are designed to limit and minimise risks to participants, and are done with strict infection control measures to limit and reduce third-party risks.


Dr Roland Chia is Chew Hock Hin Professor at Trinity Theological College (Singapore) and Theological and Research Advisor of the Ethos Institute for Public Christianity.