Covid-19: Boffins say no third wave, just yet

Some are panicking that we’re heading into the third wave of SA’s Covid-19 outbreak, while others are acting as if masks and social distancing count for nothing. But experts cautioned this week that neither approach is correct.

Professor Salim Abdool Karim, outgoing head of the ministerial advisory committee, told the Sunday Times there was “no indication of an upward trajectory compatible with a third wave”.

The overall pattern in the first year of the pandemic has been mainly consistent across provinces, but with granular differences, he said.

For example, the Western Cape was ahead of the curve in the first wave but the Eastern Cape led the second wave.

The Eastern Cape is now experiencing “small spikes in cases”, which result from small outbreaks, or, as Abdool Karim calls them, “small fires”.

The numbers are still “well below the low transmission threshold and well below the 5% test-positive proportion”.

Another flashpoint is the Northern Cape, but Abdool Karim said the numbers there did not foreshadow an imminent third wave.

“The Northern Cape, where even a few cases make a big difference, usually takes a lot longer to recover from a wave and so we cannot make anything of its fluctuations,” he said.

The sparsely populated province has been an anomaly throughout the pandemic, and peaked between the two waves when the rest of the country was seeing low transmission rates.

Wits University vaccinology professor Shabir Madhi said: “They’ve got a very different epidemic. Infections are more spread out over a longer period of time, which is a good thing as it means the health system there is not overwhelmed.”

In short, said Abdool Karim, “there is no indication that SA or any province is on its way to a third wave at this time. Every province [except for the Northern Cape] is in low transmission at present.”

Western Cape health department head Dr Keith Cloete said the province also had small outbreaks — including one in a Mitchells Plain hospital ward — against a backdrop of generally very low transmission.

“Over the past seven days we’ve seen a drop in transmission and are approaching the lowest transmission rates we saw between the first and second wave,” he said, adding that there had been a few spikes but these had all been arrested and there was an “overall picture of decline”.

But Madhi warned that SA will see the third wave soon if it let down its guard. “The positivity rate has crept up slightly to just above 5% and in two or three provinces there is a slight uptick in cases on a day-to-day basis. I wouldn’t call it a third wave but if people engage in mass gatherings then it will come sooner rather than later,” he said.

Said Cloete: “There are numerous public holidays coming up and gatherings pose a high risk of being superspreader events. This could easily lead to an early onset of the third wave.”

The experts also called for cool heads when reacting to daily statistics. Over four days last weekend Covid-19 mortality figures showed KwaZulu-Natal responsible for 44% of national deaths on Friday, 45% on Saturday, 24% on Sunday and 82% on Monday.

“I am not sure we can say it’s people suddenly dying. It could very easily be a lag in the reporting, because when you look at the deaths in KwaZulu-Natal they were disproportionately low in the first and second waves,” said Abdool Karim.

“I don’t know enough about how the data is collected. It could be a case of ‘catching up’ on numbers that even out the previous low ones that were reported.”

Likewise, in the Western Cape, the numbers suggest a high case mortality rate, but a deeper dive shows this isn’t the case.

Madhi said: “On paper, the Western Cape has the highest mortality rate, but that’s more to do with a smaller gap between reported deaths and excess deaths. It means there is more accurate reporting of fatalities.

“In some of the other provinces, the gap between reported deaths and excess deaths is as high as 60% or 70%.”

Professor Cheryl Cohen, co-head of the Centre for Respiratory Disease & Meningitis at the National Institute for Communicable Diseases, said that while there had been “substantial geographic variation in Covid-19 attack rates in different communities, there is not really a consistent pattern explained by differences between big and small provinces”.

Variations between rural and urban areas had also been inconsistent, she said. “Although overcrowding does play a role in the transmission of infectious diseases including SARS-CoV-2, other factors like social interactions in different communities and use of nonpharmaceutical interventions do play a role in shaping the epidemics.”