A new study has found that previous infection with an Omicron variant of COVID-19 did not protect seniors in long-term care and retirement homes from getting reinfected within a few months.
Senior author and McMaster University immunologist Dawn Bowdish says the study results are surprising because they challenge the current thinking about hybrid immunity.
People are expected to gain hybrid immunity to COVID-19 when they've been both vaccinated against the virus and have also been infected.
But in the McMaster study, vaccinated seniors who had been infected with Omicron variants in early 2022 were about 20 times more likely to be reinfected with another Omicron variant later that year.
That's compared to seniors who were vaccinated but had not been infected.
Bowdish says the study suggests people should stay up-to-date with their COVID-19 vaccinations and not assume a previous infection is protecting them.