Covid-19 first-of-its-kind study saw volunteers infected for science

The first “controlled investigation” of Covid-19 has been carried out and it has allowed researchers to dispel a widespread myth about the way people become infected. The human challenge study involved people being deliberately infected with a virus — in this case it was SARS-CoV-2, the virus that causes Covid-19. The study, published last week in the journal Nature Medicine, found that only the most minuscule amount of the virus is needed to infect a person — as much as a single airborne droplet from a person sneezing, coughing or talking. It also found that, despite what most people have been told, viral shedding and transmissibility occur at high levels when a person is infected regardless of whether they have severe or mild symptoms.