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South Africa’s leading scientists believe the country has established a form of herd or group immunity to COVID-19 after the number of infections unexpectedly plummeted following a major outbreak in June and July this year.
Commenting on a series of studies revealing high infection rates in the Western Cape and Gauteng provinces, the country’s leading vaccinologist Professor Shabir Mahdi told Sky News that he believed the coronavirus had stimulated a level of immunity in about 12 to 15 million people.
“What has happened in South Africa today, the only way to explain it, the only plausible way to explain it is that some kind of herd immunity has been achieved when combined with the use of non-pharmaceutical interventions … like the use of masks, physical distancing, guarantee of indoor ventilation, etc. “
At the height of the pandemic, South Africa ranked as the fifth most affected country in the world, behind the United States, India, Brazil and Russia, all of which have much larger populations.
It was at this point that Cape Town-based researchers began testing for traces of the virus in blood samples provided at local clinics by pregnant women and HIV patients.
Virologists like Dr. Marvin Hsiao were surprised to find that, on average, 40% of those surveyed had developed antibodies to the coronavirus and most did not know they had been infected.
Preliminary indications from a similar study in Gauteng, which contains the country’s largest city, Johannesburg, reveal that about a third of those tested had been infected.
“Inexplicably, the number (of people infected with COVID-19) started to decline in late July, and at that point I couldn’t explain why, “Dr. Hsiao said.
“But when we looked at the data, it became clear that this immunity within the population level (related to) the large increase in infections is probably the main reason we have seen the number of infected declines.”
During the lockdown, residents were forced to queue together to get essentials
The understanding that South African scientists have reached about achieving a level of herd immunity in their country seems to contradict a Imperial College researchers study, London, which found that the number of people with COVID-19 antibodies in the UK fell from 6% of the population in June to 4.4% in September.
His ‘React-2’ study suggests that immunity to COVID-19 may be short-lived, but Professor Mahdi challenges the importance of antibody testing, noting that it only tests a part of the human body’s immune system.
“This drop in antibodies doesn’t really tell what to expect without proper questioning of other components of the immune system. The experience with the common cold and SARS coronavirus is that T-cell immunity probably lasts 2-3 years.”
South African researchers believe that South Africa’s strict level five lockdown, which was imposed in March, inadvertently worked to start a massive wave of infection.
In the densely populated villages surrounding major cities, residents were forced to search for essentials such as food and social security payments, creating what Dr. Hsiao described as “new networks for the spread of disease.” Social distancing was practically impossible in plots where 20 or more people are often forced to live indoors.
Dr Mahdi says that the failure of the lockdown to remove COVID-19 provided the country with the unintended benefit of a temporary, or longer duration, immunization for many South Africans.
“This deficiency in terms of enforcement of the blockade, where we have inadvertently had transmission, has resulted in a high percentage in densely populated areas becoming immune.
“There could be a question in terms of the duration of immunity … based on our experience with other coronaviruses, a mild infection will probably (generate immunity) for two or three years, but that puts us in a really good position.”
Professor Shabir Mahdi says that in South Africa the blockade may have accelerated the spread of the disease
For scientists, and policy makers, there is a lot of work to be done and additional studies will be commissioned in the coming weeks with the aim of better understanding the number of people infected and how the virus has spread.
But the vaccination professor clearly believes that the development of some immunity in the population to COVID-19 was not only inevitable, but a necessary development in the South African context.
“It is not denied that COVID is the leading cause of death this year, replacing HIV, tuberculosis, and everything else, but the answer must be much more nuanced than simply believing that a highly restrictive lockdown will eliminate the virus.
“Under no circumstances will a single blockade eliminate the virus.”
