UK will run world’s first controversial Covid-19 challenge trial

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Britain has become the first country in the world to green light a controversial study where volunteers are deliberately infected with coronavirus.

The ‘human challenge trial’ will start next month in London after sealing approval from the UK’s clinical research ethics body today.

Researchers will purposefully expose up to 90 healthy adult volunteers under the age of 30 to a dose of SARS-CoV-2, the virus that causes Covid.

The study, being backed by £33.6million of taxpayer cash, will seek to establish how much viral load it takes for a person to catch the disease and how Covid progresses after infection.

These have been the burning questions during the pandemic. It’s thought the amount of virus particles someone inhales determines how sick they will be.

The Imperial College London trial will also be used to accelerate the approval of promising upcoming vaccines. Standard human jab studies currently take months because scientists need to wait for volunteers to get infected naturally.

Challenge trials are commonly deployed by scientists trying to develop a vaccine and have been used in malaria, typhoid and flu.  

Business Secretary Kwasi Kwarteng said: ‘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 take place here in the UK and will help accelerate scientists’ knowledge of how coronavirus affects people and could eventually further the rapid development of vaccines.’ 

Researchers are encouraging people aged between 18 and 30 years old, who are at the lowest risk of falling seriously unwell with Covid, to volunteer for the study.  

Triallists will only be accepted if they have no previous history or symptoms of Covid-19, no underlying health conditions and no known risk factors for the disease, such as being overweight or smoking. 

They will be infected with the original strain of coronavirus which has been circulating in the UK since last February. They will also be monitored 24 hours a day.

That strain was the dominant one across the country until this winter when it was overtaken by the highly-infectious, more deadly Kent variant. It now accounts for fewer than 20 per cent of new infections.

The researchers behind the study say they are assessing the original strain to establish a baseline before moving onto novel variants.

They told a press briefing this afternoon they chose the original strain because ‘you need to have as much information as possible’ when conducting a challenge trial, which has inherent risks.

Professor Robert Read, head of clinical and experimental sciences at Southampton University, who is involved in the study, said: ‘It’s really important to establish this model with a virus we know so much about. 

‘We know an awful lot about the original strain in UK, we know exactly the rate at which it causes complications. 

‘It [the trial of the initial strain] will show we’re able to establish infection in healthy volunteers, and most importantly if it’s safe to do that.

‘You need that information before you move onto novel variants.’

Any new treatments or vaccines will need to be able to target this variant if they are to gain approval from Britain’s medical watchdog.

However, all current Covid medicines and vaccines proven to work on the original strain have shown to be effective on the Kent one, too.    

The challenge study is being delivered by a partnership between the No10’s Vaccines Taskforce, Imperial College London, the Royal Free London NHS Foundation Trust and drug researcher hVIVO.

The research will take place in the Royal Free’s quarantine clinics in London which are specifically designed to contain infectious diseases.

The study will initially aim to help doctors understand how the immune system reacts to different levels of coronavirus and how a person who is infected with Covid-19 virus transmits infectious particles into the environment. 

But it’s hoped that vaccine candidates shown to be safe in early studies will then be trialled on the participants to accelerate their approval. 

Vaccines are normally tested using two groups of people, both of which need to contract the disease naturally, with one given the vaccine and the other used as a control. 

Traditional clinical trials require tens of thousands of participants to boost the chance of some of them being infected with coronavirus in the community.

But, in challenge trials, the pool of volunteers can be much smaller because every person is guaranteed to be infected with the disease.

Interim Chair of the Vaccines Taskforce Clive Dix 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. 

‘We expect these studies to offer unique insights into how the virus works and help us understand which promising vaccines offer the best chance of preventing the infection.’

Scientists will need to decide on a dose that infects the volunteer without causing serious illness.

This has previously been a sticking point because experts are still divided about what qualifies a ‘safe dose’ of the virus.

Some people infected with large amounts of the disease experience no symptoms at all, while others fall seriously unwell with much smaller amounts, although this is mostly the elderly and those with weakened immune systems.

It is also essential for there to be medication on standby that can prevent serious illness in participants.

So far, only a few steroids and anti-inflammatories have been scientifically proven treatment for Covid-19. But they only work on people who are extremely unwell.