Scientists and government officials are on high alert for a potential fourth wave of coronavirus infections in Gauteng, after the province reported a jump in recorded cases and an increase in several other indicators used to gauge the trajectory of the pandemic.
These include the test positivity rate and the level of SARS-CoV-2 detected in waste water samples.
The government’s response will be closely watched by businesses, as previous surges have triggered tighter lockdown restrictions, with devastating economic consequences.
The seven-day moving average of new cases recorded in Gauteng rose to 364 on Sunday, from 109 a week earlier and 70 on November 7, according to Council for Scientific and Industrial Research mathematician Ridhwaan Suliman.
Equally concerning, the test positivity rate, which measures the percentage of coronavirus tests that come back with a positive result, more than doubled in the past week to 5% from below 2%, according to Wits vaccinologist Shabir Madhi.
While these increases are off a low base, the rapid change is troubling SA’s experts.
“We are certainly very worried. The likelihood is that this is the start of a fourth wave, but we don’t want to rush to conclusions,” said Bruce Mellado, a member of the Gauteng provincial government’s advisory committee on Covid-19.
Acting health director-general Nicholas Crisp said the increase in cases in Gauteng is concentrated in Tshwane, and efforts are under way to trace and isolate contacts to try to contain the numbers.
The National Institute for Communicable Diseases (NICD) said a cluster of cases has been identified at a higher education institute, which Business Day understands to be the Tshwane University of Technology.
“We are monitoring these trends to see if these increases persist,” said NICD acting executive director Adrian Puren.
“Localised increases in case numbers [clusters] are not unexpected. However, it is hard to say whether the increases indicate the start of a widespread resurgence.”
The majority of reported cases in Gauteng are among younger people aged between 10 and 29, while the Tshwane cluster is among people aged between 20 and 44.
The NICD said last week there have been two successive increases in the levels of SARS-CoV-2 detected in waste water in Tshwane and Johannesburg.
Puren said that genomic surveillance has not at this stage detected any new variants that are displacing the Delta variant.
Previous waves have been driven by the emergence of new SARS-CoV-2 variants, each more transmissible than the last. Beta displaced the original wild-type virus to power SA’s second wave, which peaked in January, while Delta drove the third, which peaked in July.
Experts advising the government said last week that unless a new, more virulent and highly transmissible variant emerges, the fourth wave is likely to be less severe than previous waves because a high proportion of the population has some protection as a result of prior infection or vaccination. The SA Covid-19 modelling consortium said seroprevalence surveys indicate between 60% and 70% of the population has already been infected with Covid-19.
As of Sunday, 34.5% of SA’s adults were fully vaccinated.
Madhi said there is still time to mitigate the impact of a fourth wave among SA’s most vulnerable citizens, as even a single vaccine dose provides some protection against Covid-19 within a fortnight.
SA is providing adults with either a single dose of Johnson & Johnson vaccine or two doses of the Pfizer/BioNTech vaccine. Age is the single biggest risk factor for severe illness, hospitalisation and death from Covid-19, yet only 63% of women and 65% of men aged 60 and above have received at least one shot, according to the government.
A less severe fourth wave would result in fewer hospital admissions and create less strain on the health-care system, reducing the need for the government to tighten lockdown restrictions, said Madhi.
“There is little reason for the government to go to higher levels of restrictions other than hospitals being at imminent risk of being overwhelmed,” he said.
In the SA context, more stringent restrictions would not reduce the number of cases, but would only slow the spread of Covid-19, he said.
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