Author(s):
Kislaya, Irina ; Casaca, Pedro ; Borges, Vítor ; Sousa, Carlos ; Ferreira, Bibiana I. ; Fonte, Ana ; Fernandes, Eugénia ; Dias, Carlos Matias ; Duarte, Sílvia ; Almeida, José Pedro ; Grenho, Inês ; Coelho, Luís ; Ferreira, Rita ; Ferreira, Patrícia Pita ; Borges, Cláudia Medeiros ; Isidro, Joana ; Pinto, Miguel ; Menezes, Luís ; Sobral, Daniel ; Nunes, Alexandra ; Santos, Daniela ; Gonçalves, António Maia ; Vieira, Luís ; Gomes, João Paulo ; Leite, Pedro Pinto ; Nunes, Baltazar ; Machado, Ausenda ; Peralta-Santos, André
Date: 2023
Persistent ID: http://hdl.handle.net/10400.18/8950
Origin: Repositório Científico do Instituto Nacional de Saúde
Subject(s): BA.2; BA.5; COVID-19; Omicron; SARS-CoV-2; Coronavirus Disease; Death; Hospitalization; Postinfection Vaccine Effectiveness; Respiratory Infections; Severe Acute Respiratory Syndrome Coronavirus 2; Vaccine-preventable Diseases; Viruses; Portugal; Infecções Respiratórias; Doenças Evitáveis pela Vacinação; Determinantes da Saúde e da Doença
Description
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.
