Recent findings from Vietnam and Singapore, on the frontlines of the pushback against the pandemic

Covid-19 continues to ebb and flow across national borders more than a year after the pandemic’s outbreak, and Southeast Asia bears the brunt of new variants now bearing Greek names.

The SARS-CoV-2 virus is apparently evolving in response to globalised human activity and mass vaccinations.

Vietnam’s health minister Nguyen Thanh Long warned at the end of May of a “very dangerous” new variant in the country that spreads quickly by air.

It was initially thought to be a hybrid of the variants predominant in the outbreaks in India and Britain. WHO has since said that the virus in Vietnam falls under its definition of the Delta variant (also known as B.1.617.2, first detected in India), with additional mutations.

Vietnam has been a low-profile success story in curbing the pandemic by decisively clamping down on detected transmissions. It recorded 3,100 confirmed cases and just 35 deaths as of early May among its population of 98 million. However, by June 4, the numbers had radically risen to 8,747 cases and 53 deaths.

The spike in the number of infections has been marked by an increasing number of unlinked community transmission cases as well as workplace clusters discovered in industrial parks.

The Vietnamese authorities’ laboratory cultures of the variant showed that it replicates rapidly, which is thought to explain the high number of new cases appearing in different parts of the country within a short time.

In Singapore, the authorities have begun investigating the possible airborne transmission of Covid-19 in certain settings. This follows the discovery of several clusters, including at a health facility, Tan Tock Seng Hospital.

One angle being explored is that airborne transmission can occur in enclosed environments where the air cannot naturally refresh itself or that otherwise have poor ventilation.

Thus when an infected person with a high viral load enters the space and coughs, sneezes or talks animatedly, aerosols with the virus are released into the air and may be inhaled by people in the same space or even by those walking past.

This would also appear to be the case for medical procedures that produce aerosols, such as the intubation of infected patients. The national authorities have since mandated additional safeguards for hospitals, such as air filters and blowers.

The authorities are also looking into the case of a cleaner at a Stay-Home Notice (quarantine) facility for travellers despite not having direct contact with them.

Thus the cleaner may have become infected from airborne virus or via a contaminated surface after neglecting personal hygiene (perhaps from fatigue or force of habit) and had rubbed eyes or nose.

While droplet transmission (from spittle, for example) is still conventionally thought to be the main mode of transmission, it is not unlikely that droplet, surface and airborne transmissions can occur simultaneously, not least in indoor settings.