•Waning immunity from previous waves could be contributing to the earlier-than-expected resurgence in cases.
•But so far there was no sign that BA.4 and BA.5 were causing significantly more severe disease
South Africa may be entering a fifth COVID wave earlier than expected after a sustained rise in infections over the past 14 days that seems to be driven by the BA.4 and BA.5 Omicron sub-variants, health officials and scientists said on Friday.
The country that has recorded the most coronavirus cases and deaths on the African continent only exited a fourth wave around January and had predicted a fifth wave could start in May or June, early in the southern hemisphere winter.
Health Minister Joe Phaahla told a briefing that although hospitalisations were picking up there was so far no dramatic change in admissions to intensive care units or deaths.
He said at this stage health authorities had not been alerted to any new variant, other than changes to the dominant one circulating, Omicron.
Infectious disease specialist Richard Lessells told the same briefing that waning immunity from previous waves could be contributing to the earlier-than-expected resurgence in cases.
He said the rising share of infections attributed to the BA.4 and BA.5 sub-lineages of Omicron suggested they had a growth advantage over other Omicron sub-variants like BA.2.
But so far there was no sign that BA.4 and BA.5 were causing significantly more severe disease, said Waasila Jassat from the National Institute for Communicable Diseases.
South Africa has reported more than 3.7 million COVID cases and over 100,000 deaths during the pandemic. On Thursday, the WHO's Africa office flagged the rise in South Africa's infections as the main driver of an uptick on the African continent.
Senior health official Nicholas Crisp also said on Friday that the country had enough vaccine doses and was not planning to procure more. He added the government was not intending to buy Pfizer's (PFE.N) COVID treatment pill Paxlovid for public sector patients, partly because it was very expensive.