WASHINGTON – People who have been both previously infected with and vaccinated against Covid-19 get long-lasting protection against severe disease and hospitalisation, a large international study found.

The combination prevented more than 97 per cent of severe disease or hospitalisation for up to 12 months after infection or initial immunisation, whichever was most recent, according to a report from the World Health Organisation. Boosters conferred an additional six months of protection.

Meanwhile, infection alone was just under 75 per cent protective over a year.  

The report was based on a review of more than two dozen studies from January 2020 to June 2022 on protection afforded by hybrid immunity – the combination of infection and vaccination – and by previous infection alone.

The findings should be used to tailor guidance on the number and timing of Covid-19 shots, the report said.

Scheduling for updated booster shots has long been debated among health experts who disagree on intervals between vaccine doses and whether updated boosters are necessary for all age groups.

The US Food and Drug Administration is set to meet on Jan 26 with a group of outside advisers to discuss whether immunisation policies should be revised as the pandemic evolves. BLOOMBERG