What is ‘hybrid immunity’ and how well will it protect me against Covid-19?

With SA having passed the peak of the fifth wave of Covid-19 infections, epidemiologist Prof Salim Abdool Karim says “hybrid immunity” can be the best form of protection against future variants. 

According to the World Health Organization (WHO), hybrid immunity is defined as immune protection in individuals who have had one or more doses of a Covid-19 vaccine and experienced at least one SARS-CoV-2 infection before or after the initiation of vaccination.

Speaking on CapeTalk, Karim said hybrid immunity is the best form of immunity and can be a powerful response to reinfection.

“Getting Covid-19 and then the vaccine will give you the best protection against the current variant and possibly future variants,” he said.

The WHO said studies show protection conferred by hybrid immunity against infection and mild symptomatic disease is similar, or modestly better than that by infection-induced or vaccine-induced immunity alone. 

“Compared with infection-induced immunity, hybrid immunity from two or three exposures to the antigen (infection with pre-Omicron variants of concern or Omicron and one or two doses) improve immune protection against symptomatic infection due to Omicron,” said the WHO.

The organisation said hybrid immunity resulting from three or more exposures to the virus antigen — one or more exposures from vaccination and one or more from SARS-CoV-2 infections before or after vaccination — may provide superior protection as measured by neutralisation capacity. 

“Waning of hybrid immunity, particularly due to Omicron infections, is not yet characterised in magnitude or duration. 

“More data is needed for precise quantification of the immune protection from hybrid immunity compared with vaccine-induced immunity normalised for the same antigen exposure.”

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