A seroprevalence study among people who visited public health facilities for antenatal care and routine HIV tests in the Cape Town area found that 40% of respondents had antibodies against the coronavirus.
Researchers stressed that the results are preliminary and based on a skewed sample of 2 700 people in South Africa’s Western Cape province who aren’t representative of the overall population. A representative seroprevalence study last month of residents in India’s capital, New Delhi, found that 30% have had the coronavirus.
Still, the South African study, the first of its kind, suggests that “especially in poorer communities, a relatively high proportion of people has been exposed to and infected with Covid-19,” said Mary-Ann Davies, director of the Centre for Infectious Disease Epidemiology and Research at the University of Cape Town.
“Cape Town appears to have had a very pervasive Covid-19 epidemic,” she said in a briefing to reporters Thursday. “It’s likely that that high proportion of immunity at least in the short term may have played some role in curtailing the epidemic.”
Cape Town was the first South African city to experience a surge in April before the outbreak spread to the eastern and northern provinces. Today, the pressure has eased off considerably and hospitals have started to reintroduce normal clinical services, according to the Western Cape Department of Health.
The serological study was led by Marvin Hsiao, a virologist at the National Health Laboratory Service and the University of Cape Town, in collaboration with the University of Stellenbosch and the Western Cape Department of Health. Two representative household surveys — one nationwide, and one across three provinces — will be conducted by other institutions later this year.
While it’s unlikely that there will be any “explosive outbreaks” in vulnerable communities in the near future, testing criteria should be revised to detect a second wave of infections, Davies said. Proposals include the tracking of Covid-19 home deaths, pre-operation testing of asymptomatic patients and increased testing in prisons, schools and work places, she said.
South Africa has more than 633 000 confirmed cases of the coronavirus, the most on the continent.