Volunteers have been exposed to the coronavirus that causes covid-19 as part of a scientific study koto_feja/GETTY Deliberately exposing people to the coronavirus behind covid-19 in a so-called challenge study has helped us understand why some people seem to be immune to catching the infection. As part of the first such covid-19 study, carried out in 2021, a group of international researchers looked at 16 people with no known conditions who had neither tested positive for the SARS-CoV-2 virus nor been vaccinated against it. The original variant of was sprayed up their noses.
Nasal and blood samples were taken before this exposure and then six to seven times over the 28 days after. They also had SARS-CoV-2 tests twice a day. Advertisement Read more The participants fell into three groups, says team member at Cambridge Stem Cell Institute in the UK.
In one group, six people tested positive in both of their daily tests for more than two days, while also having symptoms. In another, three participants tested positive in one of their twice-a-day-tests, but not the other, for no more than two days, without symptoms. In the final group, seven people consistently tested negative for the coronavirus.
In total, the researchers looked at more than 600,000 blood and nasal cells across all the individuals. Get the most essential health and fitness news in your inbox every Saturday. They found that in the second and third groups, the participants produced interferon – a substance that he.
