People with symptomless Covid-19 could be driving the spread of the virus, researchers have said.
Experts said that people who are infected but have no symptoms may have "comparable potential" for spreading the virus as those who have symptoms – including fever, a new and persistent cough and a new loss or change of taste or smell.
The findings support the use of face coverings among the general public, the study's lead author said.
A team of researchers examined people who were at a community facility designated for the isolation of patients with mild Covid-19 in South Korea.
They evaluated patients' symptoms as well as the amount of virus they were carrying – or their viral load – in their nose and throats.
There were 213 patients without severe symptoms. Of these, 19% were asymptomatic.
Researchers found that people without symptoms had comparable viral loads to symptomatic patients.
Their study, published in the journal Thorax, concludes: "Asymptomatic individuals were frequent among those infected with SARS-CoV-2, but harboured a comparable viral load compared with that of symptomatic patients and may thus act as a meaningful driving force for the community spread of Covid-19."
In a linked podcast, lead author Professor Sung-Han Kim said the findings "support the possibility asymptomatic individuals are contributing to the ongoing community spread of Covid-19.
"The viral load was similar between asymptomatic individuals and symptomatic patients. This suggests that asymptomatic with a Sars-CoV-2 infection have a comparable potential for spreading the virus as symptomatic patients.
"Our data add further support to the general public use of face masks, regardless of the presence of symptoms, and suggest that the scope of SARS-CoV-2 testing should be expanded to include asymptomatic individuals in high-risk settings, such as nursing homes or healthcare facilities."