LONDON – In the coming weeks, a small group of carefully selected volunteers is expected to reach the 11th floor of a London hospital to receive what the rest of the world’s 7.8 billion people have been trying to avoid: a coronavirus infection.
They will receive small drops of the virus in their nostrils as part of a plan authorized by British regulators on Wednesday to deliberately infect volunteers not vaccinated with the coronavirus.
Scientists hope to eventually expose vaccinated people to the virus as a way to compare the effectiveness of different vaccines. But before that, project sponsors need to expose unvaccinated volunteers to determine the lowest dose of the virus that will reliably infect them.
By controlling the amount of viruses people are subjected to and monitoring them from the moment they are infected, scientists hope to discover things about how the immune system responds to coronavirus that would be impossible outside a laboratory – and to develop ways of comparing them. the effectiveness of treatments and vaccines.
“We are going to learn a lot about the immunology of the virus,” said Peter Openshaw, a professor at Imperial College London involved in the study. He added that the study would be able to “accelerate not only the understanding of diseases caused by the infection, but also the discovery of new treatments and vaccines”.
The idea of such a study, called the human challenge test, has been hotly debated since the first months of the pandemic.
In the past, scientists have deliberately exposed volunteers to diseases like typhoid and cholera to test vaccines. But infected people can be cured of these diseases; Covid-19 has no known cure, placing scientists responsible for the British study in a virtually unknown ethical territory.
To try to ensure that participants are not seriously ill, the British study will be restricted to healthy volunteers aged 18 to 30.
But there have been serious cases of Covid-19, even in these types of patients, and the long-term consequences of an infection are also largely unknown. Age restrictions can also make it difficult to translate the findings to the elderly or people with pre-existing illnesses, whose immune responses may be different and who are the target group 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, you’re not going to study those in whom it’s more important to know what’s going on.”
For now, the only part of the study to be formally authorized by British regulators is the experiment to determine the lowest dose of virus needed to infect people.
After being exposed to the virus, participants will be isolated for two weeks in the hospital. For this and for the value of the year of planned follow-up visits, they will receive 4,500 pounds, or about $ 6,200. The researchers said that this would compensate people for time away from work or family, without creating a huge economic incentive for people to participate.
When the idea of testing with human challenges first came up last year, some scientists saw it as a way to save crucial time in the race to identify a vaccine. Unlike large clinical trials, in which scientists expect vaccinated people to find the virus in their communities, researchers on this project would end up infecting vaccinated people on purpose.
Now that several vaccines have been authorized, the objectives of this human challenge test are slightly different.
For now, researchers will expose people to the version of the virus that has been circulating in Britain since last spring, and not to the most contagious and potentially deadly variant that has recently installed itself. But, in the end, they could give people experimental vaccines designed to deal with the effect of new and worrying variants and then subject them to these versions of the virus.
They could also directly compare different vaccine doses and dosage ranges for the same vaccine.
And once the pandemic subsides and there are fewer hospitalized patients to enroll in drug tests, the scientists behind the study said that additional tests in which people are directly infected would allow them to continue investigating new treatments.
“In the future, we will not have a large number of people that you can do field studies on,” said Robert Read, professor of infectious diseases at the University of Southampton, who helped design the study.
Infecting unvaccinated people even with low doses of the virus can yield important information, said Andrew Catchpole, the scientific director of hVIVO, a company specializing in human testing that is involved in the study.
However intensely the coronavirus has been studied, relatively little is known about how people’s immune systems react immediately after infection.
Nor do scientists yet know the specific type or level of immune response that is needed to completely protect most people from infection, a clue to how the dozens of vaccines that are still being studied will work against the virus.
“One of the things we don’t understand is what a truly protective response is,” said Lawrence Young, a virologist at Warwick Medical School, who is not involved in the study. “It’s a good way to understand the host-pathogen interaction, although it does come with a number of ethical issues, obviously.”
In the first part of the study, scientists will administer small doses of the virus to a small cohort of volunteers. If they are not infected, the scientists will give slightly higher doses to a different group of volunteers, repeating the process in up to 90 participants until they determine the right dose.
This spring, scientists hope to repeat a version of their experiment, exposing vaccinated people to the virus. The British government, which is helping to fund the study, will help choose vaccines. These and other future stages of the test would require new regulatory approvals.
There was no lack of interest among potential volunteers in these types of tests, with thousands of people worldwide registering their interest in 1Day Sooner, a group that advocates challenge tests on humans as a way to accelerate the development of sufficient vaccines. to inoculate people in parts of the world still waiting for doses
It is unclear how drug regulators in Britain or around the world would assess the results of a human test, given age restrictions and the small number of people involved.
But Catchpole said Britain’s drug regulator indicated it would take any of the group’s findings into account when evaluating future vaccine candidates.
With the virus now acquiring dangerous mutations, a question that scientists face is whether they will be able to follow its evolution.
Just as making new vaccines takes time, making new viral particles to infect people also takes time. Dr. Catchpole said that the researchers would take three or four months to make a new variant of the coronavirus in a laboratory before starting to put droplets of it on the volunteers’ nose.