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Comparative Effectiveness of COVID-19 Vaccines in Preventing Infections and Disease Progression from SARS-CoV-2 Omicron BA.5 and BA.2, Portugal

2023; Centers for Disease Control and Prevention; Volume: 29; Issue: 3 Linguagem: Inglês

10.3201/eid2903.221367

1080-6059

Irina Kislaya, Pedro Casaca, Vítor Borges, Carlos Sousa, Bibiana I. Ferreira, Ana Fonte, Eugénia Fernandes, Carlos Matias Dias, Sílvia Duarte, José Pedro Almeida, Inês Grenho, Luís Coelho, Rita Ferreira, Patrícia Pita Ferreira, João Paulo Borges, Joana Isidro, Miguel Pinto, Luís F. Menezes, Daniel Sobral, Alexandra Nunes, Daniela Santos, Antônio M. Gonçalves, Luı́s Vieira, João Paulo Gomes, Pedro Pinto Leite, Baltazar Nunes, Ausenda Machado, André Peralta‐Santos,

Vaccine Coverage and Hesitancy

Abstract We estimated comparative primary and booster vaccine effectiveness (VE) of SARS-CoV-2 Omicron BA.5 and BA.2 lineages against infection and disease progression. During April–June 2022, we implemented a case–case and cohort study and classified lineages using whole-genome sequencing or spike gene target failure. For the case–case study, we estimated the adjusted odds ratios (aORs) of vaccination using a logistic regression. For the cohort study, we estimated VE against disease progression using a penalized logistic regression. We observed no reduced VE for primary (aOR 1.07 [95% CI 0.93–1.23]) or booster (aOR 0.96 [95% CI 0.84–1.09]) vaccination against BA.5 infection. Among BA.5 case-patients, booster VE against progression to hospitalization was lower than that among BA.2 case-patients (VE 77% [95% CI 49%–90%] vs. VE 93% [95% CI 86%–97%]). Although booster vaccination is less effective against BA.5 than against BA.2, it offers substantial protection against progression from BA.5 infection to severe disease.