asymptomatic carriers are the missing link in the spread of covid-19, experts say. new studies suggest that up to 50 per cent of all covid-19 cases do not produce symptoms — or at least symptoms that are noticed by the infected people.
and because people who are asymptomatic feel fine, they are less likely to take precautions to prevent the spread to other people.
an australian
study
published in last week’s british medical journal found that over 80 per cent of the 128 people who tested positive for covid-19 were asymptomatic.
and in an
editorial
in last week’s new england journal of medicine, scientists referred to asymptomatic transmission of sars-cov-2 as the “achilles’ heel of covid-19 pandemic control.”
the reason covid-19 has been allowed to spread so successfully is that people who either didn’t notice symptoms or didn’t have any and went to work, got on planes, interacted with other people, says dr. jeffery shaman, professor of environmental health sciences at columbia university.
shaman set up a testing site at a major nyc attraction and swabbed 2500 people who were visiting the landmark.
“one in nine were shedding the virus,” he says, without knowing they were infected. despite this, many were travelling all around the city, passing it to others.