UK set to begin world’s first Covid-19 human challenge trial – but is it still necessary?

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  • The UK is ready to commence the world's first Covid-19 human challenge study
  • Ethical arguments have been made for and against infecting individuals with a potentially deadly virus
  • This study, UK officials say, will streamline and improve vaccine testing and development

The UK is officially moving forward with the world’s first Covid-19 human challenge trial, in which healthy volunteers will deliberately be exposed to SARS-CoV-2, the virus that causes Covid disease, in a carefully controlled setting.

Kicking off in the next few weeks, the government announced on Wednesday that the study will  include up to 90 healthy adult volunteers aged 18–30 years, who are at the lowest risk of harm from Covid-19.

The researchers aim to establish the smallest amount of virus it takes to sicken someone, and hope that their work will aid Covid vaccine and therapy research.

Safety of volunteers paramount

The study has been approved by the UK’s clinical trials ethics body and will take place in the high-level isolation unit of the Royal Free Hospital, London, where all participants will be quarantined and monitored closely.

Each volunteer will receive £4 500 (about R91 600) for their participation.

The study is a partnership between a number of institutions, including the UK government’s Vaccines Taskforce, Imperial College London, the Royal Free London National Health Service Foundation Trust, and the clinical company hVIVO, which has pioneered viral challenge studies.

“The safety of volunteers is paramount, which means this virus characterisation study will initially use the version of the virus that has been circulating in the UK since March 2020 and has been shown to be of low risk in young, healthy adults. Medics and scientists will closely monitor the effect of the virus on volunteers and will be on hand to look after them 24 hours a day,” the statement reads.

Human challenge trials aren’t new

Human challenge studies are nothing new in the field of medical science, with the first experiment – assessing whether a  method of vaccination, called variolation, could prevent chickenpox – dating back to the 1700s.

The World Health Organization (WHO) describes a human challenge study in the following terms: “Human challenge trials are trials in which participants are intentionally challenged (whether or not they have been vaccinated) with an infectious disease organism.”

Unlike in human clinical trials testing candidate vaccines, in challenge trials, researchers don't have to wait for volunteers to be exposed to the virus naturally.

This method of study has since helped scientists develop vaccines for diseases such as cholera, influenza (flu), and dengue fever.

A case for Covid-19 challenge trials

These trials – within the context of Covid-19 – have been met with considerable opposition by the scientific community and have sparked ethical debates around the risks of directly exposing people to a virus that is still fairly new, Health24 previously reported.

However, certain bioethicists have looked at the compelling arguments for and against conducting these trials.

In a paper published last year, Daniel Hausman, a research professor at Rutgers Center for Population-Level Bioethics, wrote that one of the objections is that since the volunteers are exposed to the virus without any vaccination, it violates the general principle that researchers ought not to expose healthy volunteers to more than minimal risks, unless the research has therapeutic value for the volunteers.

But after examining each of the arguments, Hausman concluded that “the ethical questions around potential harms are not compelling when considering the massive benefits challenge trials are expected to provide in the Covid-19 pandemic”.

Are they still necessary?

As it stands, 11 Covid vaccines have been authorised for use across several countries, with another 20 in phase 3 clinical trials. And with rapid immunisation taking place (in the UK and several other countries), there are questions around the need for challenge studies. So far, a Covid vaccine has been given to more than 16 million people in the UK.

Covid vaccine developers, such as Pfizer-BioNTech are also working on developing booster jabs to target the newer, dominant virus variants that have been found to be more infectious than older variants.

Considering that the planned study will use the original version of the virus, it may seem fruitless to continue with human challenge trials.

But UK health officials have said that the study will provide a strong foundation for speeding up future research into new variants and vaccines. This way, if newer versions of the vaccines are needed, they can reach the public sooner.

Quick results

Although scientists worldwide have made great progress in understanding Covid-19 and developing critical vaccines to protect people, “we are only partway up the mountain we need to climb”, said UK's business secretary, Kwasi Kwarteng. He added:

“While there has been very positive progress in vaccine development, we want to find the best and most effective vaccines for use over the longer term. These human challenge studies … will help accelerate scientists’ knowledge of how coronavirus affects people and could eventually further the rapid development of vaccines.”

Dr Chris Chiu, chief investigator for the trial at Imperial College London, said: “Our eventual aim is to establish which vaccines and treatments work best in beating this disease.”

Chief scientific officer at hVIVO, Dr Andrew Catchpole also stated that very useful results will be seen very quickly after the commencement of the study. “These crucial data feed directly back into how to develop effective vaccines and better treatments because they identify what type of immune response needs to be triggered,” he said.

READ | Covid-19 vaccine and human challenge trials: Are they ethical?

READ | Scientists to discuss Pfizer/BioNTech vaccine lab study which found decreased protection vs variant

READ | Kids and Covid: What a new study found

Image credit: Getty Images

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