A study released by The Lancet Infectious Diseases in collaboration with the World Health Organisation produced a systematic review of the level of immunity derived from COVID-19 infection and a mix of infection and vaccination known as ‘hybrid immunity.’
The analysis shows that hybrid immunity provides higher protection, demonstrating the advantages of vaccination even after people have had COVID-19.
The researchers say immunity from previous infection alone appears to last longer and be more effective than vaccination alone, but the combined immunity from both is the best. They say that when considering more rounds of vaccination, countries will need to consider how much immunity their populations already have.
Based on data from 26 studies, the analysis shows that protection against severe disease and hospitalisation remains high 12 months after developing hybrid immunity or infection, compared to unvaccinated and uninfected individuals.
For example, one year after developing hybrid immunity, a person had at least a 95% lower chance of getting severe COVID-19 or needing hospitalisation. In comparison, those who were infected a year ago but not vaccinated had a 75% lower chance of the same.
Protection against reinfection was lower than that against severe disease, though still substantial. Those with hybrid immunity had a 42% lower chance of being reinfected one year later. Those who had been infected before had a 25% lower chance of the same.
These findings are the product of a joint collaboration between the World Health Organization, the Unity Studies and SeroTracker.
