Coronavirus vaccine: wanted — human guinea pigs to be infected with Covid-19

Vaccine developers may have to resort to a method known as a ‘human challenge study’

Scientists are applying for permission to infect healthy volunteers with Covid-19 amid fears the number of cases in the UK has fallen so steeply that it will be difficult to test potential vaccines.

The health research company Hvivo, which runs a quarantine laboratory in east London, has joined scientists who say the world needs a vaccine so urgently that researchers should resort to a controversial method known as a “human challenge study”.

Under Hvivo’s proposals, up to 100 paid volunteers aged between 18 and 30 will take part — half will receive an experimental vaccine and half a placebo. All will be exposed to the virus and monitored for symptoms. Typically, volunteers are paid up to £3,500.

Only those with no antibodies to Covid-19 can take part. After being given either the vaccine or the placebo, participants will be kept under observation for two or three days before being exposed to the virus. If they begin to show symptoms, including a temperature, cough or loss of taste or smell, they will be treated with drugs such as the antiviral remdesivir, to try to avoid a serious illness.

Andrew Catchpole, chief scientific officer at Hvivo, said this may be the only way to develop a vaccine. “There’s a lot of concern from governments and the vaccine testers that it’s going to be difficult to test vaccines in normal conventional field trials, because not enough of the people vaccinated get exposed to the virus to tell whether it’s working or not,” he said.

Challenge studies have been part of vaccine development for many years. They are often cheaper than larger field trials, and give the scientists the chance of getting faster results.

The world’s first vaccine, for smallpox, was developed after Edward Jenner, an English physician, took samples from the cowpox sore and put it into the skin of his gardener’s eight-year-old son in 1796. Jenner then exposed the boy to smallpox, finding he did not become infected. This vaccine allowed smallpox to be eradicated, although it took nearly 200, years for the disease to disappear.

However, Jenner’s method exposed the key flaw in the challenge study model: for a virus to be eradicated, a small number of people are required to take a great risk.

Today, they are a common approach in vaccine trials for malaria, typhoid and flu. In these cases, there are treatments available if volunteers fall seriously ill. In contrast, current treatments for Covid-19 have shown mixed results. Remdesivir, developed to treat ebola, has been shown to reduce the recovery time for patients in hospital from 15 to 11 days, but a study in China was halted after it failed to show significant improvement.

“Therein lies the problem with Covid-19,” said Robin May, professor of infectious diseases at Birmingham University. “There is substantial risk involved. We can balance the odds in our favour with young respondents, but we know there are still plenty of people in that category who get a very serious disease and sometimes die, so you couldn’t guarantee complete safety.”

Despite the dangers, Catchpole said he had been contacted by groups working on 10 out of the 100 vaccines in development, several of which were in the early stages of human trials. Among those leading the race is a group led by the Jenner Institute at Oxford University, which has teamed up with AstraZeneca.

The Cambridge drug giant has agreed to supply 100 million doses of the vaccine as early as September or October, if it works. It has a trial in the UK involving 10,000 healthy volunteers, and plans to start a larger study in America involving 30,000 people.

However, last week Pascal Soriot, the chief executive of AstraZeneca, outlined how difficult field trials had become. The company has been forced to extend the trial to Brazil in an attempt to find enough people who will be exposed to the virus. “Probably the biggest issue that we face as vaccine developers is that the disease is declining,” he said.

AstraZeneca, which is the most valuable company in the FTSE 100 after its share price jumped on news of the vaccine trial, is focusing its efforts on those most likely to be exposed to the virus, including frontline health workers and care home staff. But, with infection rates falling, support is growing for more controversial methods.

Last month, the World Health Organisation released new guidance on challenge studies, suggesting the least risky group to infect would be those between 18 and 30,with a fatality rate of 0.03%.

Hvivo will now apply for permission from the UK’s Medicines and Healthcare products Regulatory Agency. It will also need to secure approval from the NHS research ethics committee.

Catchpole plans to begin manufacturing supplies of the virus in a laboratory, in preparation. “To my knowledge we’re the only people in the world actively working on this,” he said.