More Covid cases, deaths expected

RESULTS: BASED ON NATIONAL TESTING STATISTICS

‘Emergence of variant strains likely contributes to phenomenon.’

Covid-19 cases and fatalities – based on national testing statistics – are likely to increase compared to official estimates. This is according to the latest study released by the SA National Blood Service (SANBS) in collaboration with the Western Cape Blood Service.

The findings followed last year’s participation of 4 858 blood donors from the Eastern Cape, Northern Cape, Free State and KwaZulu-Natal in the SANBS seroprevalence (the level of a pathogen in a population, measured in blood serum) study.

This to determine how many people had Sars-CoV-2 antibodies – an indication of previous infection with the virus causing Covid-19.

The research found there was:

A substantial difference in the dissemination of Sars-CoV-2 infection among different race groups – most likely explained by historically-based disparities in socioeconomic status and housing conditions;

Substantial varied prevalence across race groups and between provinces, with seroprevalence among black donors several times higher compared to whites, coloureds and Asians; and

No clear evidence that seroprevalence among blood donors varied by age.

“These results show that many more people were infected than what is estimated, based on national testing statistics. This information is valuable to our government when they make Covid-19 related policy decisions.

“As has been seen in other areas, even such high seroprevalence does not guarantee population-level immunity against new outbreaks – probably due to viral evolution and waning of antibody neutralisation,” said the study.

Weighted net estimates of prevalence in the core age group, ranging from 15 to 69 by province – compared with official clinically confirmed Covid-19 case rates in mid-January 2021 – were Eastern Cape (63%), Northern Cape (32%), Free State (46%) and KwaZuluNatal (52%).

Dr Karin van den Berg, lead consultant in translational research at SANBS, said about the study: “One year into the pandemic, our understanding is still evolving almost every day.

“While this level of seroprevalence may mean that a significant amount of population-level immunity has been achieved, we know that other countries have seen large outbreaks even after such strikingly high seroprevalence was reported. The emergence of variant strains likely contributes to this phenomenon.