Hong Kong, Jan 3 As China prepares to reopen borders on January 8, it has ordered monitoring waste water as an early warning system for the Covid infection in cities, the media reported on Tuesday.
"Sewage surveillance" has appeared on China's Covid-19 directives for the first time, reports South China Morning Post.
The directive has asked local governments to test wastewater from households flowing into water treatment plants to indicate community infection levels and distribution of variants.
According to the report, at least 130 sub-lineages of the Omicron variant have been found in China in the past three months, since it relaxed zero-Covid policy.
"Local governments should track changes in positive case rates and viral loads, and conduct genomic sequencing as important indicators of new waves and variants," according to the new directive.
However, local experts have highlighted challenges in data interpretation as domestic waste water, rainwater, and treated industrial wastewater could be discharged into the same ageing pipeline system in China.
"Hundreds of millions of people living in rural areas without access to networked sanitation services might also go under-represented," says Aparna Keshaviah, principal researcher at Mathematica, a US-based research institute.
China is predicted to see two peaks in cases as Covid-19 spreads throughout the country, the first peak in mid-January and the second in early March.
The "sewage surveillance" technique was adopted by some countries in the early waves of the pandemic.
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