The world’s first COVID-19 “human challenge trial” will begin in the United Kingdom in a few weeks, following approval from the country’s clinical trials ethics body on Wednesday, Feb. 17.
The trial will involve up to 90 healthy adults aged 18–30 years who will be exposed to the original strain of the coronavirus in a safe, controlled environment to understand how the virus grows, as well as the early stages of infection before symptoms appear.
The challenge trial involves a consortium that includes researchers from Imperial College London, Royal Free London NHS Foundation Trust, the government’s vaccines taskforce and the clinical company hVIVO.
Volunteers will be required to undergo extensive screening, which will include blood tests, imaging tests, heart scans and other physical examinations, to ensure they are not vulnerable to COVID-19. Volunteers will only be accepted if they have no history of COVID-19, no underlying health issues and no risk factors like smoking.
The U.K. government has put £33.6 million towards the trial. Each volunteer will receive £4,500 over the year for their involvement. They will be quarantined at the Royal Free Hospital in London for at least 14 days. They will then be exposed to the coronavirus via drops in the nose two days after checking in.
Doctors will take nasal swabs and blood samples from them each day to monitor changes in the amount of the virus in their system, as well as to monitor their immune reactions. They can go home after two weeks but will be asked to return for follow-ups every few weeks for a year.
A challenge trial typically involves exposing healthy people to viruses. Researchers conduct such trials in order to better understand novel disease-causing viruses or to test the efficacy of a vaccine. Challenge trials have been conducted previously with many communicable diseases, including malaria, typhoid and the flu.
Due to the ethical implications and risks of challenge trials, it remains a controversial study method. Scientists have so far relied on studying participants who contracted the coronavirus from carriers. But because of lockdowns, the number of people contracting the disease among the general public is dwindling.
Scientists conducting studies on COVID-19 are left to wait for people to get infected with the virus again. Some even move to other countries where infection rates are higher in order to continue their research.
For their challenge trial, which will start within a month, researchers aim to determine the smallest amount of the coronavirus needed to cause an infection, not symptoms. The researchers also seek to understand how COVID-19 progresses after the initial infection, as well as the number of viral particles patients shed.
During their stay at the hospital, participants will undergo cognitive tests to assess how the coronavirus affects their cognitive function. Researchers will also use scratch and sniff cards to assess how the virus affects participants’ sense of smell. Loss of smell is one of the most common symptoms of COVID-19.
Should participants develop serious symptoms, they will be treated with remdesivir. Remdesivir is an antiviral medication initially developed to treat hepatitis. The United States Food and Drug Administration (FDA) approved its use last year for people hospitalized with suspected or laboratory-confirmed COVID-19.
The researchers said they will be using the original strain of the coronavirus to establish a baseline. “It’s really important to establish this model with a virus we know so much about,” said Robert Read, the head of clinical and experimental sciences at Southampton University, who is involved in the study.
Due to the inherent risks that challenge trials pose, researchers need to have as much information as possible. “[The trial] will show we’re able to establish infection in healthy volunteers,” said Read. It will also show if it’s safe to do that. “You need that information before you move onto novel variants.”
Andrew Catchpole, the chief scientific officer at hVIVO, said they could later conduct similar trials with novel variants of the coronavirus, such as the more contagious B.1.1.7 variant first detected in Kent.
Moreover, Read added that the results of the trial will help regulatory authorities understand the potential of novel vaccines vis-a-vis the established vaccines that already exist. (Related: Vaccine proponents now managing expectations as COVID-19 vaccine promise fades.)
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