SINGAPORE - The authorities are investigating the possibility that Covid-19 can be spread through airborne transmission in some settings, the Ministry of Health's director of medical services Kenneth Mak said on Tuesday (May 18).
Responding to a question about recent reports of airborne transmission and whether this had occurred at Tan Tock Seng Hospital, Associate Professor Mak said the authorities and TTSH are completing epidemiological investigations and hope to have further information to assess this possibility.
The authorities are also looking at how the virus could have spread in other clusters and settings.
"In each of the settings, we try to assess whether it could plausibly be a result of physical contact, as a result of droplet spread or... the possibility of aerosolised transmission."
Prof Mak said reports have emerged suggesting a stronger possibility of airborne transmission in certain settings, particularly closed environments with limited airflow and poor ventilation. But droplets and contaminated surfaces remain dominant ways by which the virus can transmit, he added.
As for the TTSH cluster, which saw 46 cases, Prof Mak said there may not be one single factor that contributed to the virus spreading among hospital staff and patients.
But it is plausible that some form of airborne transmission could have taken place, Prof Mak said. This could have happened if there was an infected person with a high viral load emanating a large amount of the virus, possibly supplemented by an environment associated with airborne transmission.
Health Minister Ong Ye Kung said Singapore's experience with Covid-19 showed that the most common mode of transmission is still among unmasked people in crowded environments with a lot of vocalisation and interaction, and in enclosed spaces with poor ventilation.
"These are the conditions that usually lead to big spreading events, and I think these are the settings that we should be most careful about," Mr Ong said, adding that the latest set of Covid-19 measures are deliberately aimed at stopping such activities in such settings.
He also thanked TTSH staff and urged Singaporeans to continue cheering them on. Noting that no new cases have been detected at the hospital for 14 days, or one incubation cycle of the virus, he said it is a good sign TTSH has started admitting new patients. Many staff under quarantine are also progressively returning to work this week.
However, patients and hospital staff continue to be regularly swab-tested. TTSH staff will also remain working in segregated zones and split teams in the next two weeks. He added: "It has been very difficult at this time to lose one of our hospitals, but it is recovering progressively, steadily, and there is good light at the end of the tunnel."