As countries race to develop a vaccine against the SARS CoV-2 virus, experts debated conducting ‘human challenge trials‘ in an online seminar of the Indian Council of Medical Research (ICMR). Human challenge trials involve the disease or the microorganism being deliberately injected into the participant/s.
While risky owing to the absence of a proven vaccine and a lack knowledge about the long term effects of the disease – in this case, COVID-19 – challenge trials are also faster as the direct effects of the vaccine, on the organism, different people and correlations between the three can be observed. In human clinical trials, however, volunteers are not deliberately exposed to the virus.
Over 25 doctors, epidemiologists and scientists participated in the ‘International Symposium on Novel Ideas in Science and Ethics of Vaccines against COVID-19 Pandemic’. Dr Anthony Fauci, one of the lead members of the Coronavirus Task Force of the US, opposed the idea saying it was “not necessary at this stage”, adding that exposing even young low-risk participants with no co-morbidities was still risky and was not “ethically and scientifically called for”. Gagandeep Kang, who recently retired as the executive director of the Translational Health Science and Technology Institute, said while human challenge trials have never been conducted in India, it has sparked a debate around it in government policymakers since the COVID-19 outbreak.
The comments assume significance in light of two recent developments in the US and India. In the US around 125 experts including scientists and doctors wrote to the US government’s National Institutes of Health (NIH), recommending challenge trials to advance vaccine development. It would be pertinent to note that while challenge trials have been conducted in the past century for diseases like malaria and cholera, human challenge trials for COVID-19 are not being undertaken anywhere. The Jenner Institute, which wrote the letter, however also pointed towards the need for the government to also build a compelling “ethical justification”. The Jenner Institute is working with the University of Oxford on a potential vaccine.
Prior to this in India, the ICMR had come under severe criticism earlier this month for envisaging the launch of the ‘Covaxine’ – being developed by Bharat Biotech and the National Institute of Virology (NIV) – by a deadline of August 15 in a July 2 letter to all institutes under it. Multiple scientists and doctors openly criticized the “impractical” and “unrealistic” timeframe, saying it “dented India’s scientific community’s credibility”, making it a “laughing stock”.
The letter by ICMR Director General Balram Bhargava said, “It is envisaged to launch the vaccine…latest by August 15, 2020 after completion of all clinical trials…You are strictly advised to fast-track all approvals related to initiation of the clinical trial, and ensure that the subject enrolment is initiated no later than July 7, 2020,” Bhargava said in the letter. The letter ended with saying, “Kindly note that non-compliance will be viewed very seriously.” Following the outrage, the ICMR later released a statement saying that the letter was only “meant to cut unnecessary red tape, without bypassing any necessary process, and speed up recruitment of participants.”
The Human Challenge Trial Debate
Experts like Marc Lipstitch, an American epidemiologist at Harvard University; US physician Stanley Plotkin; director of the Adrian Institute Adrian Hill, and; Nir Eyal, Director of the Center for Population-Level Bioethics (CPLB) at Rutgers University supported the introduction of challenge trials. They said the risks are automatically mitigated with the tests being conducted in controlled laboratory settings; reducing the trial to a few weeks and requiring a smaller group of people; the significantly lower costs; the scope of a head-to-head comparison between different trial vaccines; the direct effect of the vaccine on various types of persons and lastly; the existence of various other proven treatments for COVID-19 to counter the disease in the infected participants.
Randomised control trials, on the other hand, need a large number of volunteers to administer the candidate vaccine candidate which require monitoring for extended periods of time. The results of the trial can be hard to decode, as physical distancing and other infection control measures prevent trial participants from being exposed to the virus.
Eyal argued that challenge trials can be ethical if the risk of human challenge trials for COVID-19 vaccines were minimized and communicated clearly “with high quality informed consent and detailed demonstrations”. “It can be ethical in the same way that we accept medical volunteers or kidney donations. It is only a request, with very high-quality informed consent,” he said. Lipstitch also said challenge trials help poor, developing countries advance their own research and eliminate their dependency on “bully countries”.
However, opponents of challenge trials said their costs far outweighed the benefits. Peter Piot, director of the London School of Hygiene and Tropical Medicine, a recovered COVID patient himself, said that many young people have still fallen to the virus, even though they are at a relatively lower-risk. The NIH itself recommended against challenge trials after three-weeks of deliberations when its Accelerating Covid-19 Therapeutic Interventions and Vaccines (ACTIV) Vaccines Working Group concluded that the risks of human challenge trials outweighed the benefits.