A growing number of COVID-19 cases in South Korea are transmitted by people whose symptoms have not yet appeared,….or who never develop any symptoms at all.
A huge chunk of cases in the country's biggest cluster, which is related to the Sincheonji religious group, are known to have spread in this way.
This so-called "silent transmission" has been a major obstacle in South Korea's containment efforts as such patients cannot be quarantined before they spread the virus.
And it is unclear how infectious these asymptomatic patients are.
"They may be less infectious because since they don't have respiratory symptoms like coughing, so they release less droplets. But the thing is, they could do lots of outside activities without knowing they are infected."
That means these patients could cause group infections at any time, and there is no way to prevent it.
What's worse, it's also hard do contact tracing on those patients because the scope of investigation is too vague.
South Korea had previously investigated people's contact routes starting from the date that their symptoms appeared, but the guideline was later changed to a day before that, and now has moved up to two days before they start showing symptoms.
But for the more tricky cases -- patients that show no symptoms at all -- the guideline has yet to be determined.
Amid the uncertainties, the South Korean government has been focusing on one thing -- preemptive testing.
"South Korea tests the entire community when one member there is infected. That's not necessary in theory or happening much in other countries where the rest of the group would just go into self-quarantine for 2 weeks."
“The Prime Minister also told people to assume that anyone, including themselves, could potentially be an asymptomatic patient, and to practice caution at all times.
Lee Kyung-eun, Arirang News”