Study: Hybrid immunity gives better protection from Covid than just vaccines

KOCHI: As India looks at ways to combat the inevitable cyclical resurgence of Covid, a new study from Kerala shows hybrid immunity giving significantly higher protection against breakthrough infection than vaccine immunity alone.
The study also shows the probability of infection across all times being significantly lower in those with hybrid immunity than in those with immunity triggered by vaccine doses. On the other hand, the survey of healthcare workers (HCWs) reinforces what was already known - that higher antibody levels after vaccination is no guarantee against future infection. In other words, there is no correlation between high antibody levels and infection rates.
"Hybrid immunity has been associated with higher levels of neutralising antibodies and greater protection against infection than vaccines. Since this data is limited for India, we decided to conduct a study," said Dr Muhammed Niyas, associate consultant of infectious diseases at KIMSHealth in Thiruvananthapuram and the corresponding author of the study.
The study compares the incidence of lab-confirmed Covid in Covishield-vaccinated HCWs at KIMSHealth with evidence of prior infection and without prior infection. A total of 397 HCWs who received two doses of Covishield and completed four weeks post-vaccination were followed for a year till January 2022, when India started administering precaution doses.
Dr Padmanabha Shenoy, who was among the first to analyse that hybrid immunity generates 25 to 30 times more immunity than vaccines, in a paper published in Lancet last year, said, "This study validates what we had said in real-life situations too. Hybrid immunity is the key reason that India had a less severe Omicron wave compared to several other countries."