A new study claims that adults infected with the coronavirus in that first wave (March-September 2020) were 40 percent less likely to be infected during the first six months of the Omicron wave (December 2021 to May 2022). Age was also a factor, and according to the study led by Dr. Allison McGeer, University of Sinai Health System, older adults were more likely to be infected during the Omicron wave (dominated by the Ba.1 and Ba.2 sublineages) than younger adults. There was little chance of that happening. of Toronto, Canada and colleagues.
Furthermore, as expected, vaccination also provided substantial protection on top of natural immunity. “Infection with the original first-wave SARS-CoV-2 virus during March to September 2020 was associated with a 40 percent reduction in the risk of infection during the Omicron BA.1/BA.2 period from December 2021-May 2022,” the researchers said.
COVID-19 vaccination provided additional protection, and our study “showed younger individuals to be at greater risk of infection by Omicron than older age groups.” Compared to adults aged 18-49, those aged 50-64 were 36 per cent less likely to be infected, and those aged 65 and older were 66 per cent less likely.
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Multivariate modeling was used to estimate the hazard ratios of initial SARS-CoV-2 infections with and without infection, adjusting for age, sex, immunosuppression, household income, calendar time (weeks), number of vaccine doses received. , and was adjusted for time. latest dose.
The results are to be presented at the European Congress of Clinical Microbiology and Infectious Diseases (ECCMID) in Copenhagen, Denmark (15-18 April).