Researchers published the results of the first “human challenge study” regarding COVID.
The research followed participants who volunteered to be deliberately infected with the virus, allowing researchers to see what happens in the earliest stages of the infection.
The U.K. study involved 36 healthy volunteers between the ages of 18 and 30. Each was given a tiny drop of fluid containing coronavirus through a tube inserted in their nose.
They stayed for two weeks in special rooms at London’s Royal Free Hospital and were monitored 24 hours a day. Challenge studies are controversial because they involve intentionally giving someone a harmful virus.
Of 36 exposed, 18 became infected
Of the 36 exposed, 18 became infected. Two had no symptoms and the rest had mild symptoms. 83% lost their sense of smell. Six months after the study, one participant still can’t smell normally.
The findings were published in the journal Nature Medicine. One of the most significant discoveries was how little virus it takes to cause an infection.
The amount in a single droplet sneezed or coughed was enough to make someone sick, emphasizing the importance of masks that cover the nose and mouth.
Researchers also found that those infected were releasing high amounts of the virus before they showed symptoms. Most were potentially contagious for six and a half days, but some were still shedding virus on day 12.
Researchers are continuing to study the participants who didn’t get sick. Finding out why they were protected could be important in future pandemics.
The volunteers in this study were unvaccinated and had not been previously infected with COVID. Researchers say they plan to do another challenge study, this time with vaccinated people.