The South African Medical Research Council (SAMRC) has reported a worrying increase in Covid-19 fragments in wastewater treatment plants in Tshwane and Nelson Mandela Bay.
Dr Renée Street, deputy deputy director at the SAMRC's Environment and Health Research Unit, said the rising Covid-19 concentrations were evident in the majority of wastewater treatment plants in Tshwane.
In addition, she said, there was increasing volatility in Covid-19 concentrations at wastewater treatment plants where levels were previously low.
"Apart from the sharp increases in SARS-CoV-2 fragment concentrations being observed in community-based wastewater treatment plants, we are also picking up rising concentrations in wastewater samples collected from Cape Town International Airport," Street said.
The SAMRC monitors wastewater plants in four provinces weekly. On Monday mornings, field staff collect samples from the wastewater treatment plants for delivery to partner analytical laboratories by midday, for extraction and analysis. By Wednesday, after quality control checks, the findings are relayed to relevant municipal and other stakeholders. For the latest findings, the organisation worked with the Sefako Makgatho Health Sciences and Nelson Mandela Universities.
Dr Rabia Johnson, Deputy Director of the SAMRC's Biomedical Research and Innovation Platform, said the picture changed dramatically at the end of October.
"At the beginning of the month, levels of SARS-CoV-2 RNA fragments in wastewater were mostly low or undetectable; now we're measuring concentrations last seen during the third Covid-19 wave."
The SAMRC has warned that the rapidly increasing concentrations of Covid-19 RNA fragments in wastewater were a major cause for concern, especially alongside reports of increases in Covid-19 cases and deaths in the past week.
"Collectively, the evidence makes a compelling case for those who qualify for booster shots to get them urgently," said Professor Glenda Gray, SAMRC chief executive.
Gray said the severity of the fourth wave of Covid-19, predicted to start in December, will depend on the number of people who are vaccinated.
She urged healthcare workers to get booster shots.