What is it about?
During the COVID-19 pandemic, population immunity could develop through vaccination, natural infection, or a combination of both. We investigated SARS-CoV-2 seropositivity among healthcare workers in Pretoria, South Africa, during the fourth wave of the pandemic, when the Omicron variant was dominant. Using laboratory-based testing for antibodies against the SARS-CoV-2 spike and nucleocapsid proteins, we examined whether detectable antibodies were more consistent with vaccination or previous natural infection.
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Why is it important?
Almost all of the healthcare workers studied had detectable antibodies against SARS-CoV-2, but most of this detectable immunity was associated with vaccination. Among 221 participants, 96% had at least one SARS-CoV-2 antibody subtype, with 76% showing a pattern consistent with vaccine-derived immunity and 23% showing evidence of previous natural infection. Participants with evidence of both vaccination and previous infection had significantly higher antibody levels than those without evidence of natural infection. These findings provide a snapshot of immunity among South African healthcare workers during the Omicron wave and highlight the contribution of vaccination even in a population with substantial exposure to natural infection.
Perspectives
Immunity to SARS-CoV-2 is dynamic, with antibody levels changing over time and being influenced by both vaccination and infection. Our findings support the continued importance of vaccination for healthcare workers and demonstrate the value of serological surveillance in understanding population immunity during evolving waves of infection. Further studies are needed to understand how antibody waning, repeated infection, vaccination and other components of the immune response contribute to longer-term protection.
Dr Catherine Worsley
University of Pretoria
Read the Original
This page is a summary of: SARS-CoV-2 seropositivity amongst healthcare workers in South Africa during the Omicron wave: natural infection versus vaccination, Journal of Clinical Pathology, January 2025, BMJ,
DOI: 10.1136/jcp-2024-209722.
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