COVID -19 And Ethics Of Human Challenge Trials

As laboratories around the world race to develop a vaccine for the novel coronavirus, many people have volunteered to take part in a controversial testing method called human challenge trials. The method, which involves intentionally infecting volunteers with the novel coronavirus, is being promoted in order to speed up the process of preparing a vaccine.

Human Challenge Trials

  • To understand these trials, it is imperative to know the actual process of developing vaccine which is a three-stage process.
  • In Phase 1, small groups of people receive the trial vaccine.
  • During Phase 2, the clinical study is expanded and the vaccine is given to people who have characteristics (such as age and physical health) similar to those for whom the new vaccine is intended.
  • In Phase 3, the vaccine is given to several thousand people and tested for efficacy and safety. During this phase, participants either receive the vaccine or a placebo. The efficacy of the vaccine is determined by comparing the prevalence of infection in the group that was administered the vaccine with the one which received a placebo. The hypothesis that those in the vaccine group will be infected significantly less is thus tested.
  • Under human challenge trials, participants of both the vaccine group and placebo group upon consent are deliberately exposed to the infection – thus are “challenged” by the disease organism.

Arguments in Favour of Human Challenge Trials

  • Such trials could save valuable time in developing a Covid-19 vaccine, as researchers would not have to wait for participants to contract the infection under real-world conditions. Replacing Phase 3 with human challenge trials may subtract many months from the licensure process, making efficacious vaccines available more quickly.
  • According to experts, such testing would also require a significantly smaller number of people than regular Phase 3 trials, which require thousands of volunteers.
  • The speed of HCTs and the richness of the data they provide in a clinical setting will accelerate the development of an effective and broadly accessible Covid-19 vaccine, with thousands or even millions of lives spared (depending on the pandemic’s long-term trajectory).

Ethical Concerns over Human Challenge Trials

  • While human challenge trials are not new, they are usually carried out in developing medications for diseases which are considered less lethal and have been better understood by scientists over the years, such as malaria. Critics have questioned undertaking such trials for Covid-19, a potentially deadly disease for even those who are less at risk, and which researchers are still in the early stages of studying.
  • In a 2016 document WHO has raised concerns that HCTs can be in conflict with the guiding principle in medicine to do no harm.

Way Forward

  • Although human challenge trials provide valuable scientific knowledge, it is essential that challenge studies be conducted within an ethical framework in which truly informed consent is given.
  • When conducted, human challenge studies should be undertaken with abundant forethought, caution, and oversight. The value of the information to be gained should clearly justify the risks to human subjects. Information to be gained should clearly justify the risks to human subjects.