Source avec lien : The Lancet Infectious Diseases, (En ligne). 10.1016/S1473-3099(22)00578-3
Il existe peu de données sur l’immunité induite par le vaccin ou par l’infection (hybride ou naturelle) contre la sous-variante BA.2 de l’omicron (B.1.1.529), notamment en ce qui concerne la comparaison des effets d’une infection antérieure par le SRAS-CoV-2 de même lignée génétique ou différente. Nous avons cherché à estimer la protection contre l’omicron BA.2 associée à une infection primaire antérieure par l’omicron BA.1 ou le pré-omicron SARS-CoV-2, chez les travailleurs de la santé avec et sans vaccination par ARNm.
Background There is a paucity of data on vaccine-induced or infection-induced (hybrid or natural) immunity against omicron (B.1.1.529) subvariant BA.2, particularly in comparing the effects of previous SARS-CoV-2 infection with the same or different genetic lineage. We aimed to estimate the protection against omicron BA.2 associated with previous primary infection with omicron BA.1 or pre-omicron SARS-CoV-2, among health-care workers with and without mRNA vaccination. Methods We conducted a test-negative case-control study among health-care workers aged 18 years or older who were tested for SARS-CoV-2 in Quebec, Canada, between March 27 and June 4, 2022, when BA.2 was the predominant variant and was presumptively diagnosed with a positive test result. We identified cases (positive test during study period) and controls (negative test during study period) using the provincial laboratory database that records all nucleic acid amplification testing for SARS-CoV-2 in Quebec, and used the provincial immunisation registry to determine vaccination status. Logistic regression models compared the likelihood of BA.2 infection or reinfection (second positive test ≥30 days after primary infection) among health-care workers who had previous primary infection and none to three mRNA vaccine doses versus unvaccinated health-care workers with no primary infection.