South Africa has reached some sort of herd immunity against COVID-19, but that was achieved in the context of the use of non-pharmaceutical interventions.
This is the view of Professor Shabir Madhi from the school of pathology at the University of the Witwatersrand. Madhi is also the director of the Medical Research Council’s Vaccines and Infectious Diseases Analytics Research Unit (VIDA).
The number of new confirmed COVID-19 cases in South Africa peaked in July 2020 at around 14,000 per day.
Since then there has been a steady decline, which started to plateau in September at between 1,000 and 2,000 new cases per day.
The only plausible way to explain this decline, Madhi told Sky News, is that some sort of herd immunity has been reached.
Madhi said the coronavirus has “stimulated a level of immunity in approximately 12 to 15 million people” in South Africa.
Dr Nei-yuan (Marvin) Hsiao, a virologist at the University of Cape Town, shed further light on the immunity which Madhi is referring to.
His team tested for traces of the virus in blood samples from pregnant woman and HIV patients, and found much higher levels of infections than expected.
Hsiao told Sky News “on average 40% of respondents had developed coronavirus antibodies with the majority being unaware that they had been infected”.
A similar study in Gauteng found around one third of people who were tested showed that they had been infected with the virus.
These studies confirmed an earlier finding by Madhi during the preparation COVID-19 vaccine trials in South Africa.
Mahdi said they faced an unexpected challenge – far more people were infected but asymptomatic than previously thought.
He said between 50% and 66% of adults who are infected with COVID-19 are completely asymptomatic.
“The majority of COVID-19 infections are going unnoticed,” Mahdi said, adding that only around 10% of all COVID-19 cases are officially reported.
This information, Hsiao said, explains why there was an unexpected decline in coronavirus infections in South Africa.
“This immunity within the population level linked to the surge of infections is probably the main reason why we’ve seen the decrease of numbers of infected,” Hsiao said.
Health Minister Dr Zweli Mkhize recently expressed concerns around a rising number of COVID-19 cases in South Africa.
Mkhize said this increase will be considered by the Department of Health as it makes new recommendations to the government’s National Coronavirus Command Council (NCCC).
KwaZulu-Natal premier Sihle Zikalala went one step further recently, warning of a second hard lockdown unless the number of cases decline.
“We can now safely say that we are definitely going back into a hard lockdown if there is no urgent and drastic change in behaviour,” said Zikalala.
Madhi, however, advised against a second hard lockdown in the case of a new wave of COVID-19 infections.
“The response has to be much more nuanced rather than simply believing that the highly restrictive lockdown is going to get rid of the virus,” he said.
“Under no circumstances is a lockdown on its own going to achieve the elimination of the virus.”