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What is behind the rise in unlinked COVID-19 cases in Singapore?

What is behind the rise in unlinked COVID-19 cases in Singapore?

People wearing protective face masks while crossing a road on May 24, 2021, during Phase 2 (Heightened Alert). (File photo: Marcus Mark Ramos)

SINGAPORE: The rise in unlinked COVID-19 cases in Singapore could be due to logistical issues, such as the effort needed to contact trace higher numbers of infections, or it could be a signal that the virus is more common for now, experts told CNA.

According to the latest update from the Ministry of Health (MOH) on Tuesday (Jul 27), of the 136 new locally transmitted COVID-19 cases in Singapore, 55 were unlinked. 

Overall, the number of unlinked cases in the community increased to 182 in the past week from 46 in the week before, according to MOH's update on Tuesday night.


READ: 136 new locally transmitted COVID-19 cases in Singapore, including 55 unlinked


While many cases start off unlinked and become linked later, “we expect more unlinked cases for a few reasons”, said Professor Dale Fisher, senior consultant at the Division of Infectious Diseases at the National University Hospital.

Prof Fisher, who is also chair of the World Health Organization’s Global Outbreak and Alert and Response Network, said that one possibility is that the increase in overall cases may make contact tracing "a little slower".

The overall number of infections increased 50 per cent in the past week compared to the week before, according to Tuesday's update. With 902 cases linked to it, the Jurong Fishery Port/Hong Lim Market and Food Centre cluster is the largest active cluster in the country.

Prof Fisher said that another reason for the rise in cases could be that “there is just more virus around”.

“So (this means) more contaminated surfaces, therefore the contact between people is indirect,” he said.

He also pointed to the nature of the Delta variant of the coronavirus that has been picked up among COVID-19 cases, including those from the fishery port - the variant requires lesser exposure to transmit.

He added that people could be transmitting the virus despite being asymptomatic or having “very mild” symptoms.

Unlinked cases refer to those where it is not clear how the patients got infected, said Prof Fisher.

“They could be a person who has not been to any of the sites where there are active clusters and they don’t live with or work with a known case but they have a test because they have mild symptoms. Obviously, they caught it from someone but we can’t recognise that link,” he said.

President of the Asia Pacific Society of Clinical Microbiology and Infection Professor Paul Tambyah said that the number of unlinked cases is a “concern” as it may reflect new clusters that are beginning to emerge. However, it could also be due to the challenge of establishing the source of people's infection against the backdrop of more daily cases. 

“It could mean either that there are too many cases every day so the team finds it hard to link the cases quickly … The number does vary from day to day so it is possible that this is just a logistic issue,” he said.


Prof Tambyah said that there are challenges in bringing the situation under control. Among them is that the largest active clusters have significant numbers of “floating populations” who are difficult to track down and “in fact may not want to be tracked”.


READ: Timeline: From KTV lounges switching to F&B outlets, to a spike in local COVID-19 cases


“As such, novel approaches to outreach need to be considered to ensure that they do not end up seeding new clusters in other locations,” he said.

Health Minister Ong Ye Kung said on Monday in Parliament that the KTV lounge cluster that emerged on Jul 12  is "coming under control", with low daily numbers linked to it.

Prof Tambyah said that the current situation is different from last year’s as “we have effective vaccines which means that the chances of severe infection and death are markedly reduced”.

He added that Singapore has “much better diagnostics and systems in place, including self tests and antigen tests which means that we can find cases a lot faster”.

“Finally, we have come to the realisation with many other countries that this virus has become endemic, like all other pandemics in history,” he said.

“The focus then should be on protecting the vulnerable and preserving the healthcare system rather than trying to aim for zero COVID-19, which is practically unattainable without paying a huge price in terms of economics, mental health and having a severe impact on the rest of the healthcare system.”

Prof Fisher said that the current strategy is to keep a lid on the number of cases so that the country can complete the vaccination roll-out.

He noted that giving seniors a choice is “interpreted by some that vaccination is not important”.

According to the latest updates from MOH, about 77 per cent of seniors above the age of 70 have received at least the first dose of a vaccine. Attempts are being made to further increase that number because older people are more vulnerable. 

“As a result, we are seeing older people getting severe illness and in some cases dying. Also, in slowing down the country’s opening, they are impacting the livelihoods of those who are vaccinated and that’s not fair,” he said.

“It may be that we need to be more firm with our unvaccinated older folk."


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Source: CNA/ja


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