New cluster in Hougang may be linked to past cases

The cluster of Covid-19 cases in Hougang Avenue 8 could possibly be linked to previous infections in the area, but experts say cryptic cases that contribute to such scenarios are to be expected.

Cryptic cases refer to those patients who have gone undetected so far, and are also unaware they are infected.

The cluster involves a Giant supermarket in Block 683 and was first announced on Thursday.

There were several outbreaks in the area in May and June with swab tests carried out for residents, visitors and shop staff.

Professor Teo Yik Ying, dean of the National University of Singapore's (NUS) Saw Swee Hock School of Public Health, told The Sunday Times that the current cluster's link to previous clusters is now "less relevant".

Singapore, he said, should expect to see more clusters emerging as vaccination rates rise.

"We should not be so concerned about where or when someone got infected, as this is part and parcel of learning to live with endemic Covid-19," he said.

A disease that is endemic is one that remains permanently in the community, such as influenza.

"When someone catches the flu, they are not so concerned about where they caught it from, because it is endemic. A similar attitude should apply to Covid-19 here in the future," Prof Teo added.

Prof Dale Fisher, a senior consultant at the National University Hospital's Division of Infectious Diseases, said: "Actually, cryptic spread is our future and will be quite normal in the endemic phase."

Both experts noted that unlike previous outbreaks in Hougang, there has been no call for mass testing in the area to date.

This reflects a shift in Singapore's strategy towards tackling the virus in future, they said.

Prof Fisher, who is also a professor of medicine at NUS' Yong Loo Lin School of Medicine, said: "Past responses have necessarily been harmful socially and economically to individuals and to the nation. They had to be to save lives.

"Now that the threat to life is much less because of the vaccine, our responses from the past are not needed."

He said with the majority of Singapore residents now safe from severe disease, the future is not about finding every case, shutting businesses and putting people in quarantine. "It is about minimising spread through sensible actions that don't impact people excessively."

Prof Teo said contact tracing will not cease completely. It will instead be modified to focus on high-risk groups, and in locations frequented by high-risk people, as well as in specific settings, including healthcare settings and migrant worker dormitories.

The area around Hougang Avenue 8 had seen a rash of cases previously, with residents, visitors and shop staff having to take swab tests. But Prof Teo said despite rigorous testing efforts, the current cluster may be linked to the previous infections in the area.

First, some cases could have been missed by the tests because they either did not reside or work in the locations targeted for mass testing, or happened to be in the incubation phase of the virus during the period of testing.

Second, cryptic spread could have occurred through vaccinated individuals who did not realise they were infected, as such people are more likely to have no or only mild symptoms.

Prof Fisher said the unvaccinated in the area should pay heed.

"They need to understand that there will be a lot of (the coronavirus) around as restrictions are eased - and they are not protected by others being vaccinated."