ADF STAFF
South Africa’s newest wave of COVID-19 infections is proving to be substantially different from previous waves. This is partly because of the high level of immunity in the population, according to experts from the country’s National Institute for Communicable Diseases (NICD).
The new wave, which is being driven by the BA.4 and BA.5 sublineages of the omicron variant, differs from previous waves in several ways:
- While infection levels are high, hospitalization levels remain low.
- Deaths remain much lower than previous waves, peaking slightly higher than the lowest point for previous waves.
- The current wave is happening while South Africa has eliminated all mandatory protective measures such as masking and social distancing.
It’s also significant that the current wave is being caused by sublineages, not by a new variant as previous waves were.
Exposure to both those earlier variants and to the original omicron variant appear to have granted a certain level of immunity to about 90% of South Africans. The new sublineages have been able to cause reinfections in some people, but symptoms have generally been milder, according to public health experts.
“The current patterns demonstrate that in a context such as South Africa with high levels of population immunity, it is possible to have a substantial surge in transmission that does not overwhelm the health system, even without putting new restrictions in place,” Dr. Michelle Groome, head of the NICD’s Division of Public Health Surveillance and Response, wrote in The Conversation.
With winter moving into the Southern Hemisphere, Southern Africa is experiencing rapid growth in cases caused by BA.4 and BA.5. Botswana, Eswatini and Namibia all have reported sharp increases alongside South Africa.
That growth has been enough to reverse the continent’s overall decline in cases over the past two months. New cases were up an average of 36% in May, according to the Africa Centres for Disease Control and Prevention.
Recent studies of the new omicron strains show that, although they can produce mild infections in those with immunity, they can be as dangerous as other variants for those with no protection.
Research by the South African Medical Research Council showed excess deaths — the estimate of deaths above historic norms — starting to tick upward slightly, but in numbers far smaller than in any previous waves.
Data from the NICD published in late May suggests that the current wave already has peaked and begun to retreat. Although case positivity was as high as previous waves, the average infection rate of less than 15 per 100,000 population is much lower than the original omicron wave, which peaked at just under 40 per 100,000 at the end of 2021.
South Africa’s current experience with the omicron strains could become the model for future seasonal waves of infection, Groome wrote.
“Moving forward, we expect that case numbers will rise and fall,” Groome wrote. “What matters now is whether there is sufficient monitoring in place to detect major changes in time to respond.”
Close monitoring of infections will help keep the health care system ahead of future waves, preventing them from overwhelming hospitals and clinics, according to Broome.
Meanwhile, South Africa’s experience could portend an end to the pandemic phase of COVID-19.
“The shift to resurgences driven by sublineages rather than new variants potentially heralds a change in the evolutionary pattern of the virus and a move to it becoming endemic,” Groome wrote.
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