South Africa’s Covid-19 positivity rate slightly down, but still thousands of new cases

New cases of SARS-CoV-2 infections in South Africa increased by 4,146 between Wednesday and Thursday, with Gauteng still accounting for most of the new infections in the country, followed by KwaZulu-Natal. 

According to the latest update on a possible fifth outbreak of infections in South Africa, the National Institute for Communicable Diseases’ (NICD’s) Sinenhlanhla Jimoh said the positivity rate came down slightly from 21.1% to 18.3%. 

A winter wave of Covid-19 had been predicted for May in South Africa.  

The NICD’s report stated that the seven-day average was 18.3% on Thursday, higher than Wednesday (18.0%) and there had been a significant increase in the average number of cases over the previous seven days. 

There had been an increase of 64 hospital admissions in the previous 24 hours and on Thursday 2,027 people were in hospitals with Covid-19 complications. Of these, 251 needed oxygen and 62 were undergoing mechanical ventilation. Nationally, 192 people were in intensive care units and 149 in high care units, according to the latest report on hospital admissions and deaths due to Covid-19 complications.

During the fourth wave, doctors noted that despite a sharp increase in cases, there had not been a sharp increase in deaths and patients needing intensive care or ventilation. 

Gauteng still accounts for most cases in the country, with 53%, followed by KwaZulu-Natal with 23% and the Western Cape with 11%. The Free State accounted for 4% of cases and the Eastern Cape, Mpumalanga and North West each accounted for 2%, while Limpopo and Northern Cape each accounted for 1%.  

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Epidemiologist and infectious disease specialist Professor Salim Abdool Karim said in his weekly update that cases had risen dramatically in South Africa and the seven-day moving average of cases had just passed the threshold he uses for defining the start and end of a wave (five cases per 100,000 of the population as a daily average).

“Also, test positivity has shot up to well above 10%. I know that it is still April and that I previously said that I expected the fifth wave to start in early May, based on an inter-wave period of about 13 weeks (three months). The current increase is occurring 11 weeks [after] the end of the fourth wave. But the current increase is not all that it seems at first glance, as there is a high level of uncertainty as to what exactly is driving the current surge in cases in South Africa,” he said. 

Dr Nicole Wolter from the NICD said earlier this week that their thinking is that two sub-lineages of the Omicron variant, BA.4 and BA.5, were responsible for the spike in cases. 

“It is not unusual to detect new Omicron sub-lineages. As SARS-CoV-2 continues to spread, it continues to evolve and gain mutations. When a group of genomes all contain the same set of mutations, they are designated as a new lineage. 

“There are many sub-lineages of Omicron (including BA.1, BA.2 and BA.3 detected during the fourth wave). While BA.4 and BA.5 are new Omicron sub-lineages, they do not represent a new SARS-CoV-2 variant and are currently still classified as Omicron,” she said. DM/MC