SINGAPORE: The National Environment Agency (NEA) is expanding its wastewater surveillance programme to cover more than 400 sites by next year, the agency announced on Thursday (Jul 8).
Wastewater testing is a "non-intrusive" way to detect COVID-19 transmission in a community and supports the monitoring and management of the coronavirus, NEA said.
Since February last year, more than 200 sites have been placed under surveillance, including workers' dormitories, student hostels, welfare and nursing homes, as well as residential sites.
In a pilot programme launched last year, wastewater testing was used to support the monitoring and management of COVID-19 transmission among foreign workers living in 20 large dormitories.
"With the clearance of transmission in dormitories, wastewater surveillance today complements rostered routine testing of individuals for early detection of COVID-19 transmission in dormitories, to facilitate early intervention and isolation of cases," NEA said.
This form of testing was extended to residential sites in July last year and was first deployed in Tampines, leading to the detection of COVID-19 cases in a residential block there.
More recently, COVID-19 viral fragments were found in wastewater from several neighbourhoods, including in Bukit Merah View, Hougang and Yishun, prompting the authorities to conduct swab tests on residents and visitors. NEA said more than 15 cases were detected in June this year.
"The absence of COVID-19 viral fragments in wastewater also provides an added assurance that the sites are free from infection, and allows us to direct our testing resources in a more targeted and effective way," said the agency.
When there is a COVID-19 cluster, NEA will conduct testing for a period of time until the wastewater samples test negative for the virus, the agency added.
NEA said it also conducts surveillance at regional nodes across Singapore "for wide-area surveillance of the community", similar to the monitoring of wastewater signals at the water reclamation plants.
"Information collected from these sites provides a sense of the prevalence of infections in the community," NEA said.
Surveillance sites are selected based on a number of factors, including the suitability of the sewage network for sampling, the likelihood of viral shedding in waste from the population sampled, and the ability to trace and identify new infections at the site surveyed.
In a Facebook post on Thursday, Health Minister Ong Ye Kung said wastewater surveillance helped "identify possible transmission clusters early" and minimised spread to the community.
"So while this method cannot detect an infected individual, it is a very good early warning system, which enabled us to proactively conduct swab operations at Hougang, Yishun and Bukit Merah View to reduce further transmission to the wider community," he said.