South African studies reveal high levels of natural immunity is the best defense against omicron

Two new studies from South Africa found that the country has a lower hospitalization rate for Wuhan coronavirus (COVID-19) infections caused by the post-vaccine omicron variant. High levels of natural immunity among South Africans stemming from prior COVID-19 infections is likely a contributing factor to this.Since the appearance of the post-vaccine omicron variant, mainstream media outlets have tried to speculate regarding the variant’s virulence and deadliness. They repeatedly ignored South African health authorities, including Health Minister Joe Phaahla, who said that hospitalizations caused by omicron are “relatively low” and that the world has nothing to worry about.

According to data from South African health authorities, COVID-19 cases in South Africa have skyrocketed in recent weeks, in line with the emergence of the post-vaccine omicron variant. But what has puzzled scientists studying the data is that the country’s hospitalization rate has risen at a significantly slower pace compared to previous waves. (Related: In the age of Omicron, the jabbed are now catching & spreading COVID at a higher rate than the unvaxxed.)

The data strongly suggests that people diagnosed with omicron in South Africa were around 80 percent less likely to be admitted to the hospital than those diagnosed with any other COVID-19 variant.

Once admitted to the hospital, patients infected with omicron have a lower chance of developing severe disease. They are also hospitalized for fewer days on average than other COVID-19 patients.

In the first 31 days of the current post-vaccine outbreak, the country recorded 164,911 new COVID-19 cases. But just 3,432 patients were admitted to hospitals for additional care. One-hundred and ninety-four died.

In comparison, during the first 31 days of the previous wave, 38,577 COVID-19 cases were recorded and 10,088 were admitted to hospitals. The death rate of that wave was also more than three times higher than the death rate of the current wave, with 668 deaths in the first 31 days.

High vaccination rates unlikely to protect countries against omicron

“We believe that the evolution of cell-mediated immunity from prior natural infection … is resulting in the uncoupling of the high case rates seen with the omicron variant and the rates of severe disease,” wrote South African researchers in one of the new studies conducted on the outbreak in the country.

They added that the immunity “is primarily due to natural infection.”

While the authors included several caveats in their assessment regarding South Africa’s outbreak, they wrote that it is “difficult to disentangle the relative contribution of high levels of previous population immunity versus intrinsic lower virulence to the observed lower disease severity.”

“Compellingly, together our data really suggest a positive story of a reduced severity of omicron compared to other variants,” said Cheryl Cohen, an epidemiology professor for the University of the Witwatersrand and a member of the National Institute for Communicable Diseases in South Africa and an author for one of the studies.

Cohen believes the data is generalizable to other countries in Sub-Saharan Africa which have similar levels of previous infection and vaccination.

“I think what is unclear is how the picture will be similar in countries where there are high levels of vaccination but very low levels of previous infection,” she said. “The baseline epidemiology is different. But I think, compellingly, our data really suggests a positive story of a reduced severity of omicron compared to other variants.”

By Arsenio Toledo