TY - JOUR
T1 - Comparative complete scheme and booster effectiveness of COVID-19 vaccines in preventing SARS-CoV-2 infections with SARS-CoV-2 Omicron (BA.1) and Delta (B.1.617.2) variants
T2 - a case–case study based on electronic health records
AU - PT COVID-19 group
AU - Kislaya, Irina
AU - Peralta-Santos, André
AU - Borges, Vítor
AU - Vieira, Luís
AU - Sousa, Carlos
AU - Ferreira, Bibiana
AU - Pelerito, Ana
AU - Gomes, João Paulo
AU - Leite, Pedro Pinto
AU - Nunes, Baltazar
AU - Machado, Ausenda
AU - Rodrigues, Ana Paula
AU - Peixoto, Vasco Ricoca
AU - Casaca, Pedro
AU - Fernandes, Eugenia
AU - Rodrigues, Eduardo
AU - Ferreira, Rita
AU - Isidro, Joana
AU - Pinto, Miguel
AU - Duarte, Sílvia
AU - Santos, Daniela
AU - Meneses, Luís
AU - Almeida, José Pedro
AU - Matias, Ana
AU - Freire, Samanta
AU - Grilo, Teresa
N1 - Funding Information:
The acquisition of sequencing equipment and reagents used in this study by the Instituto Nacional de Saúde Doutor Ricardo Jorge was partially funded by the HERA project (grant no. 2021/PHF/23776), supported by the European Commission through the European Centre for Disease Control, and also partially funded by the Genome PT project (grant no. POCI‐01‐0145‐FEDER‐022184), supported by COMPETE 2020–Operational Programme for Competitiveness and Internationalisation, Lisboa Portugal Regional Operational Programme, Algarve Portugal Regional Operational, under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund, and by the Portuguese Science and Technology Foundation. The Algarve Biomedical Center Laboratory received public funding through the Project ALG‐D2‐2021‐06 Variants Screen in Southern Portugal–Monitoring Variants of Concern in Southern Portugal and the Portuguese Science and Technology Foundation national support through the Comprehensive Health Research Center (grant no. UIDP/04923/2020). Funding information
Funding Information:
The acquisition of sequencing equipment and reagents used in this study by the Instituto Nacional de Saúde Doutor Ricardo Jorge was partially funded by the HERA project (grant no. 2021/PHF/23776), supported by the European Commission through the European Centre for Disease Control, and also partially funded by the Genome PT project (grant no. POCI-01-0145-FEDER-022184), supported by COMPETE 2020–Operational Programme for Competitiveness and Internationalisation, Lisboa Portugal Regional Operational Programme, Algarve Portugal Regional Operational, under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund, and by the Portuguese Science and Technology Foundation. The Algarve Biomedical Center Laboratory received public funding through the Project ALG-D2-2021-06 Variants Screen in Southern Portugal–Monitoring Variants of Concern in Southern Portugal and the Portuguese Science and Technology Foundation national support through the Comprehensive Health Research Center (grant no. UIDP/04923/2020).
Publisher Copyright:
© 2023 The Authors. Influenza and Other Respiratory Viruses published by John Wiley & Sons Ltd.
PY - 2023/3
Y1 - 2023/3
N2 - Background: Information on vaccine effectiveness in a context of novel variants of concern (VOC) emergence is of key importance to inform public health policies. This study aimed to estimate a measure of comparative vaccine effectiveness between Omicron (BA.1) and Delta (B.1.617.2 and sub-lineages) VOC according to vaccination exposure (primary or booster). Methods: We developed a case–case study using data on RT-PCR SARS-CoV-2-positive cases notified in Portugal during Weeks 49–51, 2021. To obtain measure of comparative vaccine effectiveness, we compared the odds of vaccination in Omicron cases versus Delta using logistic regression adjusted for age group, sex, region, week of diagnosis, and laboratory of origin. Results: Higher odds of vaccination were observed in cases infected by Omicron VOC compared with Delta VOC cases for both complete primary vaccination (odds ratio [OR] = 2.1; 95% confidence interval [CI]: 1.8 to 2.4) and booster dose (OR = 5.2; 95% CI: 3.1 to 8.8), equivalent to reduction of vaccine effectiveness from 44.7% and 92.8%, observed against infection with Delta, to −6.0% (95% CI: 29.2% to 12.7%) and 62.7% (95% CI: 35.7% to 77.9%), observed against infection with Omicron, for complete primary vaccination and booster dose, respectively. Conclusion: Consistent reduction in vaccine-induced protection against infection with Omicron was observed. Complete primary vaccination may not be protective against SARS-CoV-2 infection in regions where Omicron variant is dominant.
AB - Background: Information on vaccine effectiveness in a context of novel variants of concern (VOC) emergence is of key importance to inform public health policies. This study aimed to estimate a measure of comparative vaccine effectiveness between Omicron (BA.1) and Delta (B.1.617.2 and sub-lineages) VOC according to vaccination exposure (primary or booster). Methods: We developed a case–case study using data on RT-PCR SARS-CoV-2-positive cases notified in Portugal during Weeks 49–51, 2021. To obtain measure of comparative vaccine effectiveness, we compared the odds of vaccination in Omicron cases versus Delta using logistic regression adjusted for age group, sex, region, week of diagnosis, and laboratory of origin. Results: Higher odds of vaccination were observed in cases infected by Omicron VOC compared with Delta VOC cases for both complete primary vaccination (odds ratio [OR] = 2.1; 95% confidence interval [CI]: 1.8 to 2.4) and booster dose (OR = 5.2; 95% CI: 3.1 to 8.8), equivalent to reduction of vaccine effectiveness from 44.7% and 92.8%, observed against infection with Delta, to −6.0% (95% CI: 29.2% to 12.7%) and 62.7% (95% CI: 35.7% to 77.9%), observed against infection with Omicron, for complete primary vaccination and booster dose, respectively. Conclusion: Consistent reduction in vaccine-induced protection against infection with Omicron was observed. Complete primary vaccination may not be protective against SARS-CoV-2 infection in regions where Omicron variant is dominant.
KW - case–case design
KW - COVID-19
KW - Delta variant
KW - Omicron variant
KW - SARS-CoV-2
KW - vaccine effectiveness
UR - http://www.scopus.com/inward/record.url?scp=85150531666&partnerID=8YFLogxK
U2 - 10.1111/irv.13121
DO - 10.1111/irv.13121
M3 - Article
C2 - 36935845
AN - SCOPUS:85150531666
SN - 1750-2640
VL - 17
JO - Influenza and other Respiratory Viruses
JF - Influenza and other Respiratory Viruses
IS - 3
M1 - e13121
ER -
