In a surprising finding, a recent study conducted by McMaster University has revealed that previous infection with the Omicron variant of COVID-19 did not provide protection against reinfection for seniors in long-term care and retirement homes. The study challenges the current understanding of hybrid immunity, which suggests that individuals who have been both vaccinated and previously infected gain stronger protection against the virus.
The study focused on 750 vaccinated seniors in long-term care and retirement homes across Ontario. It found that seniors who had been infected with the Omicron variant in early 2022 were about 20 times more likely to be reinfected with another Omicron variant later that year compared to vaccinated seniors who had not been previously infected.
These results imply that individuals should not assume that a previous infection offers complete protection and should continue to stay up-to-date with their COVID-19 vaccinations. However, the study does not provide insights into whether these findings are applicable to the general population or specific to seniors.
According to senior author and McMaster University immunologist Dawn Bowdish, this study highlights the gaps in our understanding of how the virus infects people. It challenges the assumption underlying Canada's vaccination strategy that a recent infection provides short-term protection against reinfection.
The study's findings were published in eClinicalMedicine, a medical journal affiliated with The Lancet. Bowdish, who holds the Canada Research Chair in Aging and Immunity at McMaster University, emphasizes the need for further research to gain a comprehensive understanding of the virus and its impact on different populations.
It is important to note that this content is solely responsible for Canadian Press health coverage and receives support through a partnership with the Canadian Medical Association. The study's findings serve as a reminder that there is still much to learn about COVID-19 and the effectiveness of different measures in preventing reinfection.