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Race on to study new mutations as Omicron BA.4 and BA.5 likely cause of 5,000 new SA Covid cases overnight

Daily Maverick logo Daily Maverick 2022/04/26 Estelle Ellis

The number of coronavirus infections in South Africa jumped by 5,000 on Tuesday 26 April 2022, with a slight drop in the positivity rate to 18%. Experts say they believe sub-lineages of the Omicron variant are responsible for the current spike in cases. Now, the race is on for them to understand how BA.4 and BA.5 are evading immunity due to prior infection and vaccination.

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While most new cases of coronavirus infections are still registered in Gauteng and KwaZulu-Natal, Dr Nicole Wolter of the National Institute for Communicable Diseases said two of the sub-lineages of the Omicron variant – known as BA.4 and BA.5 – have different mutations to other Omicron sub-lineages. 

This might indicate that these lineages can escape some of the body’s immune defences, Wolter said, adding that this could lead to an increase in the number of Covid cases and potentially a fifth wave.

“The Network for Genomic Surveillance in South Africa continues to closely monitor SARS-CoV-2 variants and sub-lineages circulating in SA. Work is also ongoing to determine the impact of the BA.4 and BA.5 mutations on the virus,” she added.

Wolter said an increase in the number of Covid cases and the proportion of cases testing positive has been observed in some provinces in recent weeks, which appear to be due to the BA.4 and BA.5 sub-lineages. 

“We have not observed an increase in hospitalisations. However, the situation is being monitored closely,” she said, adding that South Africa has high levels of immunity due to previous infection and vaccination, which has been shown to protect against the risk of developing severe Covid-19 disease. 

“There is currently no indication that this will change with BA.4 and BA.5,” she said.

Wolter said it was too early to definitively know if there are any new symptoms associated with these sub-lineages. 

“However, given that these sub-lineages are still classified as Omicron, it is likely that symptoms will be similar,” she said. 

“Vaccination remains effective at preventing severe disease, and individuals are strongly encouraged to be vaccinated and receive appropriate booster doses according to the latest Covid-19 vaccination recommendations.”

In the daily update from the National Institute for Communicable Diseases, spokesperson Sinehlanhla Jimoh said the country had registered 5,062 new Covid cases on Tuesday. She said 18% of tests done on Tuesday were positive.

Fifteen new deaths due to complications from Covid-19 were reported, but these figures might be old as the National Department of Health is still busy with an audit of death figures. Six of these deaths occurred in the last 24 hours.

The majority of new cases are from Gauteng (46%), followed by KwaZulu-Natal (29%). The Western Cape accounted for 11%; Free State and Eastern Cape each accounted for 4%; Limpopo, Mpumalanga and North West each accounted for 2% and Northern Cape accounted for 1% of new cases.

There have also been 83 new hospital admissions in the past 24 hours. DM/MC

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