No community cases in two weeks but not time to get complacent

Zero locally transmitted cases were reported in Singapore in the past two weeks. This is the longest period without any cases in the community since the pandemic started.

“I think it is a good milestone, and it gives us cautious optimism that our current measures, even in Phase Two, are sufficient to reduce the transmissibility of the virus significantly to the point where probably the majority of small outbreaks might burn themselves out,” said Associate Professor Hsu Li Yang, Vice Dean (Global Health) and Programme Leader (Infectious Diseases).

“But I stress the word ‘cautious’ here because countries such as China and New Zealand have also reached the same stage and beyond in the past, only to deal with very large outbreaks of COVID-19 that reappeared in their populations,” he added.

Although the number of locally transmitted cases has tapered off, it is not time to get complacent as there may be asymptomatic infections lurking in the community.

“Getting zero cases does not mean we have reached zero infections,” said Associate Professor Alex Cook, Vice Dean (Research).

“There could still be a very small number of undetected asymptomatic or mildly symptomatic cases that are circulating, and may seed further community cases,” added Dean, Professor Teo Yik Ying.

“Unless there is widespread and routine testing like what we do for migrant workers in dormitories, it will be difficult to identify asymptomatic cases in the community,” said Prof Teo.

There is also a chance of imported infections seeping into the community. Assoc Prof Cook noted that most imported cases will be detected, but a small fraction may not be.

Some who get infected shortly before flying into Singapore will have a long incubation or latent period before the virus manifests itself, and that causes them to test negative on their exit swab at the end of their quarantine, he said.

“Even with 14 days of strict quarantine and an exit test, a small percentage of infected travellers will pass undetected. That is why I don’t get too excited about reaching zero cases — there is always a risk of spill-over from importations,” he added.

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