LONDON – In the coming weeks, a small, carefully selected group of volunteers is expected to arrive on the 11th floor of a London hospital to learn what the world's remaining 7.8 billion people have tried to avoid: coronavirus infection .
Tiny droplets of the virus are given into their noses as part of a plan approved by UK regulators on Wednesday to intentionally infect unvaccinated volunteers with the coronavirus.
The scientists hope to eventually expose vaccinated people to the virus to compare the effectiveness of different vaccines. Before doing so, however, the project's supporters must expose unvaccinated volunteers to determine the lowest dose of the virus that will reliably infect them.
By controlling the amount of virus people are exposed to and monitoring from the time they are infected, scientists hope to discover things about how the immune system reacts to the coronavirus that would be impossible outside of a laboratory – and ways for a direct one Compare the effectiveness of treatments and vaccines.
"We will learn a great deal about the immunology of the virus," said Peter Openshaw, a professor at Imperial College London who was involved in the study, on Wednesday. He added that the study would be able to "not only accelerate understanding of diseases caused by infections, but also accelerate the discovery of new therapies and vaccines".
The idea of such a study, dubbed the Human Challenge Challenge, has been hotly debated since the early months of the pandemic.
In the past, scientists have deliberately exposed volunteers to diseases such as typhoid and cholera to test vaccines. But infected people could be cured of these diseases. Covid-19 has no known cure, which puts the scientists responsible for the UK study into largely unknown ethical territory.
To ensure participants do not get seriously ill, the UK study is limited to healthy volunteers aged 18 to 30 years.
But these types of patients also had severe Covid 19 cases, and the long-term consequences of an infection are also largely unknown. The age restrictions can also make it difficult to extrapolate the results to older adults or people with pre-existing medical conditions, whose immune responses may be different, and who are the target audience for treatments and vaccines.
"It will be a limited study," said Ian Jones, professor of virology at the University of Reading, who is not part of the study. "And you could argue that, by definition, it won't investigate those where it is most important to know what is going on."
Currently the only part of the study that has been officially approved by UK regulators is the experiment to determine the lowest dose of virus needed to infect humans.
After exposure to the virus, participants will be isolated in hospital for two weeks. They will be paid £ 4,500, or about $ 6,200, for this and the one-year scheduled follow-up appointments. The researchers said this would compensate people for their absence from work or family without creating too much economic incentive for people to participate.
Feb. 17, 2021, 6:04 p.m. ET
When the idea of human challenge experimentation first came out last year, some scientists saw it as a way to cut the crucial time in the race to identify a vaccine. Unlike large clinical trials where scientists wait for vaccinated people to encounter the virus in their communities, researchers in this project would end up infecting vaccinated people on purpose.
With multiple vaccines approved, the goals of this human challenge study are slightly different.
For now, researchers will expose people to the version of the virus that has been circulating in the UK since last spring, rather than the contagious and potentially more deadly variant that has become more prevalent more recently. But eventually, they said, they could give people experimental vaccines to combat the effects of new, more worrisome variants, and then expose them to those versions of the virus.
You could also directly compare different vaccine doses and dosing intervals for the same vaccine.
And once the pandemic wears off and fewer patients have to attend drug trials in the hospital, the scientists behind the study said that additional such trials, where people are directly infected, would allow them to keep exploring new treatments.
"Going forward, we won't have many people to study with locally," said Robert Read, professor of infectious diseases at the University of Southampton, who helped shape the study.
Infecting unvaccinated people with even low doses of the virus could provide important insights, said Andrew Catchpole, chief scientist at hVIVO, a company that specializes in human challenge trials and is involved in the study.
As intensively as the coronavirus has been investigated, little is known about how people's immune systems react immediately after infection.
Scientists do not yet know the types or levels of immune responses required to completely protect most people from infection. This is an indication of how dozens of vaccines that are still under study are doing against the virus.
"One of the things we don't understand is a really protective response," said Lawrence Young, a virologist at Warwick Medical School who is not involved in the study. "It's a great way to understand the host-pathogen interaction, although there are obviously a lot of ethical issues."
In the first part of the study, the scientists will give tiny doses of the virus to a small cohort of volunteers. If they don't get infected, the scientists give slightly larger doses to another group of volunteers and repeat the process on up to 90 participants until they find the right dose.
By spring, the scientists hope to be able to repeat a version of their experiment by exposing vaccinated people to the virus. The UK government, which is funding the study, will help choose the vaccines. This and other future phases of the trial would require new regulatory approvals.
There was no shortage of interest among potential volunteers for this type of study. Thousands of people around the world have expressed their interest in 1Day Sooner, a group committed to human challenge trials to expedite the development of enough vaccines to vaccinate people in parts of the world still waiting for doses
It's not clear how drug regulators in the UK or around the world would rate the results of a human challenge study given the age restrictions and small number of people involved.
Dr. However, Catchpole said the UK Medicines Agency said it would take the group's findings into account when evaluating future vaccine candidates.
With the virus now adopting dangerous mutations, scientists wonder whether they can keep up with its development.
Just as it takes time to make new vaccines, it also takes time to make new virus particles to infect humans. Dr. Catchpole said it would take the researchers three or four months to make a new variant of the coronavirus in a laboratory before they could start putting droplets of it into volunteers' noses.