Study Shows 98% of South Africans Carry Antibodies to COVID-19

ADF STAFF

More than two years into the COVID-19 pandemic, nearly the entire population of South Africa has some level of immunity to the virus that causes the disease, according to a study by the country’s largest blood bank.

Researchers with the South African National Blood Service (SANBS) recently reported that 98% of South Africans carry COVID-19 antibodies in their blood. The vast majority of those — 87% — have natural immunity developed in response to an infection. The remainder acquired their immunity from medication, said Marion Vermeulen, a virologist who oversees the blood service’s transfusion medicine and technical services.

The SANBS covers seven South African provinces, including populous Guateng and Eastern Cape. Western Cape province has its own blood service.

Vermeulen told South Africa’s eNCA news station that the new immunity figure was the result of the blood service’s third study of antibody levels in donated blood. The study was conducted in March after the first omicron wave. Previous studies were done in March and November of 2021 after the beta and delta waves.

In each study, volunteer donors agreed to participate after they voluntarily came in to donate, Vermeulen said.

The three studies show a rapid increase in immunity levels, from 50% in March 2021 to nearly 70% in November 2021 to 98% now. The study also suggests that there was a large occurrence of reinfection due to omicron.

“We weren’t expecting such a big increase this time around on such a high-level background,” Vermeulen said. “So, we were very surprised to see this jump.”

One major difference between the latest wave and previous waves: increased numbers of children admitted to hospitals with COVID-19. About 17% of hospital admissions during the fifth wave were children, according to South African insurer Discovery Health Ltd.

Early in the pandemic, researchers found a significant difference in exposure levels when comparing highly urbanized areas such as Guateng with more rural provinces. By March 2022, that difference had virtually vanished, Vermeulen said.

“There is no statistically significant gap in regions anymore,” she said.

The difference in infection levels between those able to work from home early in the pandemic and those who could not also has disappeared, she added.

Vermeulen said the March 2022 study was the first to differentiate between natural immunity and that acquired through medication.

South Africa’s National Institute for Communicable Diseases (NICD) reported in early June that the country was exiting its most recent wave of COVID-19 infections, this one driven by the BA.4 and BA.5 strains of the omicron variant. The wave lasted just less than 60 days and produced just less than 8,000 daily cases at its peak.

The new strains showed a strong ability to overcome immunity, particularly among people whose previous infections were by earlier COVID-19 variants. Despite that, hospitalizations and deaths during the fifth wave were lower than in any previous wave, with deaths ticking slightly above normal levels, according to NICD data.

Public health experts believe the country’s widespread immunity to COVID-19 helped shorten the time frame and impact of the fifth wave.