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Volume 29, Number 3—March 2023

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

Irina Kislaya1Comments to Author , Pedro Casaca1, 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, Cláudia Medeiros Borges, Joana Isidro, Miguel Pinto, Luís Menezes, Daniel Sobral, Alexandra Nunes, Daniela Santos, António Maia Gonçalves, Luís Vieira, João Paulo Gomes, Pedro Pinto Leite, Baltazar Nunes, Ausenda Machado2, and André Peralta-Santos2
Author affiliations: Instituto Nacional de Saúde Doutor Ricardo Jorge, Lisbon, Portugal (I. Kislaya, V. Borges, C. Matias Dias, S. Duarte, L. Coelho, R. Ferreira, J. Isidro, M. Pinto, D. Sobral, A. Nunes, D. Santos, L. Vieira, J.P. Gomes, B. Nunes, A. Machado); Comprehensive Health Research Centre, Lisbon (I. Kislaya, C. Matias Dias, B. Nunes, A. Machado, A. Peralta-Santos); Direção-Geral da Saúde, Lisbon (P. Casaca, E. Fernandes, P. Pita Ferreira, P. Pinto Leite, A. Peralta-Santos); Unilabs, Porto, Portugal (C. Sousa, J.P. Almeida, L. Menezes, A. Maia Gonçalves); Algarve Biomedical Center Research Institute, Faro, Portugal (B.I. Ferreira, I. Grenho); Administração Central do Sistema de Saúde, Lisbon (A. Fonte, C.M. Borges)

Main Article

Table 2

Crude and adjusted odds ratios of vaccine infection breakthrough in BA.5 case-patients compared with BA.2 SARS-CoV-2 case-patients, Portugal, epidemiologic weeks 17–23, 2022*

Category BA.5, no. (%) BA.2, no. (%) Crude OR 
(95% CI) Adjusted† OR (95% CI)
Vaccination status
Unvaccinated 590 631 Referent Referent
Complete primary vaccination 2,530 2,434 1.11 (0.98–1.26) 1.07 (0.93–1.23)
Booster dose
0.80 (0.71–0.89)
0.96 (0.84–1.09)
Previous infection
No 11,073 14,536 Referent Referent
1.88 (0.71–2.06)
1.44 (1.30–1.60)
Vaccination status accounting for previous infection
Unvaccinated without previous infection 468 (3.8) 550 (3.6) Referent Referent
Unvaccinated with previous infection 122 (1.0) 81 (0.5) 1.77 (1.30–2.41) 1.77 (1.26–2.49)
Complete primary vaccination without previous infection 1,802 (14.6) 1,982 (12.9) 1.07 (0.93–1.23) 1.08 (0.92–1.26)
Complete primary vaccination with previous infection 729 (5.9) 452 (2.9) 1.90 (1.60–2.25) 1.70 (1.40–2.05)
Booster without previous infection 8,805 (71.5) 12,004 (78.0) 0.86 (0.76–0.98) 0.99 (0.86–1.14)
Booster with the previous infection 382 (3.1) 327 (2.1) 1.37 (1.13–1.66) 1.18 (0.95–1.47)

*OR, odds ratio. †Adjusted for age group, sex, region, and week of diagnosis.

Main Article

1These first authors contributed equally to this article.

2These authors contributed equally to this article.

Page created: December 31, 2022
Page updated: February 19, 2023
Page reviewed: February 19, 2023
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