The Medical Research Council (MRC) has warned of a sustained increase in Covid-19 detected in wastewater samples from Nelson Mandela Bay, and urged vulnerable members of public to use masks in crowded indoor spaces and ensure they are up to date with their vaccinations.
The MRC routinely monitors more than 80 wastewater treatment sites in six province, as rising concentrations of SARS-CoV-2 RNA provide an early warning sign of increasing cases in communities that rely on the sewage networks linked to these sites.
People infected with SARS-Cov-2, the virus that causes Covid-19, shed virus in their stool even if they are asymptomatic. These viral fragments are not infectious, and people cannot catch Covid-19 from waste water. Scientists from the MRC Wastewater surveillance and research programme collects water samples every Monday.
MRC scientist Angela Matthee said there had been unusual volatility in the concentrations of SARS-Cov-2 RNA detected in the past few weeks, but there was a clear and sustained increase in Nelson Mandela Bay. Half the waste water sites in the municipality had shown increased concentrations of SARS-Cov-2 RNA three weeks in a row, she said.
“Now is a good time to take basic precautions, especially if people are (at) high risk. Mask up for indoor events, be more fastidious about hand hygiene and make sure you are up to date for vaccines and boosters,” she said.
The concentration SARS-CoV-2 RNA in water samples from the City of Cape Town on October 10 had tapered off after the sharp increase detected the week before, she said.
The MRC sounded the alarm on October 8 after detecting an unusually large increase in SARS-CoV-2 RNA concentrations in water samples collected on October 3 from sites in Cape Town and several other Western Cape towns, including De Doorns, Rawsonville and Worcester.
These increases had coincided with an increase in the test-positivity rate reported by the National Institute of Communicable Diseases, said Matthee. “The last time concentrations were this high was during the fourth and fifth waves,” she said.
The latest data also shows a spike in the concentrations of SARS-Cov-2 RNA detected in one waste water treatment site in Limpopo, she said.
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