COVID-19: Human Challenge Study Receives Ethics Approval

Peter Russell

February 17, 2021

The UK will become the first country in the world to run a COVID-19 human challenge study following approval by the UK's clinical trials ethics body, the Health Research Authority.

The study will help doctors understand how the body's immune system reacts to the SARS-CoV-2 virus and identify factors that influence how the virus is transmitted, including how an infected person transmits infectious virus particles into the environment.

Recruitment of up to 90 healthy individuals aged 18 to 30 is currently underway ahead of a trial start date within the next few weeks.

The human challenge study, backed by £33.6 million from the UK Government's Vaccines Taskforce, will be run by a partnership including Imperial College London (ICL), the Royal Free London NHS Foundation Trust, and hVIVO, an industry specialist in the testing of vaccines and antivirals.

"This main first trial is all about determining the lowest amount of virus that we can administer to determine infection," explained Dr Andrew Catchpole, chief scientific officer at hVIVO.

Doctors will be using a medical grade version of the original SARS-CoV-2 virus that has been in circulation in the UK since March 2020. It was chosen because more is known about this version of the virus than any of the new variants that have since emerged.

Future Vaccine Research

Data from the study will subsequently be used for vaccine efficacy testing, as well as to answer a wide range of scientific questions that are not possible with traditional field trials, such as what type of immunological response is required to confer protection from re-infection.

"The current vaccines may not actually be the last vaccines that we use globally," said Prof Robert Read, head of clinical and experimental sciences within medicine at the University of Southampton.

He told a briefing hosted by the Science Media Centre: "We have to give ourselves the potential to test new vaccines very quickly, and that's really the primary purpose of this effort."

He added: "We need to know about why this virus causes the effects that it does, and we need to know quite a lot more about what are the natural immune factors that lead you to be resistant, or not, to infection by this virus.

"And the only way that you can do that efficiently is with a human challenge model."

Two Weeks' Isolation in London Hospital

Thousands of people have already applied to take part in the trial which will pay volunteers £4500 for participation over 12 months.

However, fewer than 30 people have so far been recruited due to stringent eligibility criteria.

Volunteers who pass an interview and medical checks will be invited to check in at London's Royal Free Hospital for a further 2 days of medical assessments.

Dr Chris Chiu/ICL

Dr Chris Chiu, chief investigator, and honorary consultant in infectious diseases at ICL, explained what would happen next. "A couple of days after they arrive, assuming all those tests are fine, they will receive the virus as drops in the nose." Afterwards, "they lie flat on their back for half an hour, and then potentially they may be infected after that".

For the next 14 days, they will live in isolation, visited only by medical staff, who will carry out blood tests, nasal swabs, tests for sense of smell, and cognitive tests to check on reaction times.

Participants will be allowed to go home after 14 days in quarantine, with regular check-ups over the rest of the year.

As a precaution, as soon as volunteers start shedding virus from their nose, or start developing symptoms of COVID, they will receive the antiviral medication remdesivir. 

'New Insights' Into Virus and Treatments

Clive Dix, interim chair of the Vaccines Taskforce, said: "We have secured a number of safe and effective vaccines for the UK, but it is essential that we continue to develop new vaccines and treatments for COVID-19."

Lawrence Young, a virologist and professor of molecular oncology at the University of Warwick, said: "This study will allow us to understand more about the dose of SARS-CoV-2 virus needed to infect an individual and to analyse the immune response under controlled conditions.

"It will also help us to better determine the activity of various vaccine candidates and to possibly investigate differences in response to infection with virus variants."

Dr Charlie Weller, head of vaccines at Wellcome, said the human challenge trial would "provide key insights into how COVID-19 affects us from as soon as we are infected, which will potentially inform research into new treatments".


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