Scientists from the SA Medical Research Council’s (SAMRC) wastewater surveillance team have detected declining concentrations of SARS-CoV-2 RNA fragments in the majority of wastewater treatment plants across SA.
The SAMRC’s wastewater surveillance team conducts weekly sampling and analysis of wastewater from 72 wastewater treatment plants in urban and rural areas in Gauteng, Limpopo, Eastern Cape and Western Cape as a way to measure levels of the virus across SA.
The SAMRC said it is seeing levelling off or declining concentrations of SARS-CoV-2 RNA fragments in 89% of the wastewater treatment plants that it monitors in urban areas Buffalo City, Cape Town and Nelson Mandela Bay, and 97% of wastewater treatment plants in rural areas in Limpopo, the Eastern Cape and the Western Cape.
On Wednesday the Western Cape reported a slowdown in Covid-19 infections — the peak in that province is expected in three to nine days’ time — with the fourth wave in Gauteng, driven by the Omicron variant, having already peaked at about 90% of the cases of the third wave.
The fourth wave in SA has been much milder, with far fewer hospital admissions and fatalities.
Hospital admissions in Gauteng had peaked at about 50% of those of the third wave and excess deaths.
The milder fourth wave may indicate Omicron causes less severe illness, but this might also be because the SA population has high levels of immunity from previous infections and vaccinations.
“The declining concentrations of SARS-CoV-2 RNA in wastewater are encouraging,” said Prof Glenda Gray, president of the SAMRC, “but should not be viewed as an indication that we may drop our guard”.
Gray urged people to wear masks, avoid crowds and gatherings and hold essential gatherings outdoors or in well-ventilated spaces.
She also called on people to be vaccinated and for those who are eligible to get booster shots.
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