Seroprevalence studies showed an excess of 70% of South Africans had been exposed and had underlying immunity to Covid-19, Groome said. Photographer: Armand Hough/African News Agency(ANA)
Cape Town - Studies how that around 70% of South Africans are estimated to have been exposed to the virus, the National Institute for Communicable Diseases said, noting an under-reporting of antigen tests.
The NICD held a media briefing on Thursday, titled Covid-19: Decoding the Science. Among the speakers were the head of the NICD public health surveillance and response division, Dr Michelle Groome; public health specialist Dr Waasila Jassat; and Centre for Respiratory Disease and Meningitis head Professor Cheryl Cohen.
The NICD reported 3 332 008 laboratory-confirmed cases of Covid-19.
Groome said the seven-day moving average reported by the NICD included PCR and antigen tests, with an under-reporting of antigen tests.
“We know that this is an underestimate of the number of people who have had Covid-19, so we think that we are underestimating this and really only diagnosing or laboratory confirmation of only one in 10 to one in 15 people who are actually having Covid-19 infections,” Dr Groome said.
“While you’re seeing this three million, you really need to be cognisant that this is just a small proportion of the true number. There’s a lot of asymptomatic infections, there’s a lot of people who don't test for certain reasons.
“We know that our testing itself does have some differences by provinces and private versus public sector, as well as individual choices of whether to test or not.”
Seroprevalence studies showed an excess of 70% of South Africans had been exposed and had underlying immunity to Covid-19, Groome said.
Cohen said early data suggested that Omicron infections were less severe than Delta infections in South Africa.
“The reduced severity could be, in part, as a result of high levels of population immunity due to previous infections and/ or vaccinations. It could also reflect that the virus itself is less likely to cause severe illness,” he said.
The Omicron variant has overtaken the Delta variant and has become most dominant in all provinces.
Jassat said that compared to previous waves, the fourth wave was reporting the most cases, at 366 571, with the least percentage of cases admitted for hospitalisation across all waves, at just 5.7%.
The number of death was also the lowest during the fourth wave, at 5.6% compared to 19.0% during the first wave, 20.9% during the second and 22.3% during the third.
The number of people who died in hospital was 4 400 during the first wave, 4 053 during the second, 3 575 during the third and 821 during the fourth.
The number of outcomes for severe disease is the lowest in the fourth wave at nearly 4 000 compared to just over 10 000 during the previous three waves.
The NICD has seen a decrease in the seven-day moving average in the past week, indicating a decrease in the daily number of Covid-19 cases, particularly in Gauteng, North West Limpopo and Mpumalanga, with some provinces experiencing an increase in Covid-19 cases.
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