Researchers in the UK have been working on a low-risk dose of the coronavirus for human trials.
In the next phase, they'll expose willing participants to the virus to see how their immune defenses hold up.
This kind of study, while not without risks, could help inform future vaccine development.
A team of researchers at the University of Oxford is hoping to study how the coronavirus affects people who have previously been exposed, either by vaccination or natural infection. To do so, they'll need some volunteers.
Britain was the first country to approve a human challenge trial, where researchers deliberately expose participants to a pathogen that may make them sick, back in February 2021. Such a design comes with obvious risks, but it's a unique way to study the immune response to a virus and potentially improve future vaccines.
Since April 2021, a research team headed by Oxford vaccinology professor Helen McShane has been testing out various doses to determine the minimum amount of virus needed to trigger an immune response.
"We have learned a lot about COVID over the past two years, but the emergence of new variants means that we will probably have to keep refining the vaccines," McShane said in a news release from the university. "If we know what level of immune response we need the vaccine to induce, it will make future vaccine development much quicker and much more efficient."
Their aim is to have about 50% of participants test positive on a nose and throat swab with minimal to no symptoms, according to the release.
Now that the team says it is close to finding that perfect dose, the researchers are seeking volunteers for the second phase of the trial.
Phase 2 involves infecting young, healthy participants
Researchers will infect participants with SARS-CoV-2 — the technical name for the novel coronavirus — via nasal drops and observe how their immune systems respond to the threat.
The team is working with the original strain of SARS-CoV-2 discovered in Wuhan, China, that was also used to formulate the vaccines. The virus looks very different today. It has since mutated into variants like Omicron, which experts have described as typically causes milder, cold-like symptoms compared to the flu-like illness and respiratory distress seen at the start of the pandemic.
There are safeguards in place to avoid severe illness. The study is only enrolling participants aged 18-30 who are in "excellent health." Participants must be vaccinated, recovered from COVID-19, or both. Anyone who develops symptoms will be given Regeneron's monoclonal antibody treatment Ronapreve.
The risk of death from COVID-19 for someone in that age group is around one in 3,000, according to one analysis by The Guardian — that's about the same risk level that comes with donating a kidney.
The real challenge might be getting through more than two weeks in isolation: three days alone at home, two days in quarantine pre-exposure, then at least 14 days of quarantine post-exposure.
"It's basically like being in lockdown again, it's just you're being paid for it," Emily, a COVID-19 challenge trial participant, said in a video produced by Oxford. "And you're helping a really good cause to hopefully never go into lockdown again."
Participants also stand to gain a large sum of money — at least £4,995, or about $6,690 — as compensation for their time and inconvenience.
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