Effectiveness of CoronaVac primary series with and without booster against hospitalized COVID-19 during the Omicron-predominant epidemic wave in the Philippines: a test-negative case–control study

Background CoronaVac (Sinovac) was initially effective against symptomatic COVID-19 and severe outcomes, but its performance against the immune-evasive Omicron variant remains uncertain. This study evaluated the effectiveness of CoronaVac against hospitalized COVID-19 among Filipino adults during th...

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Main Authors: Kristal An Agrupis, Michelle Ylade, Yang Yang Qi, Maria Vinna Crisostomo, Jedas Veronica Daag, Gianne Lariz Magsakay, Jude Raphael Lo, Kiarah Louise Florendo, March Helena Jane Lopez, Jayne Marie Enriquez, Irish Lobitaña, Gretchen Bonita Ranada, Regina Alfonso, Mitzi Marie Chua, Mitzie Lou Osabel, Mary Ann Igoy-Bacay, Carren Anne Bocaling, Lorenz Von Seidlein, Xuanyi Wang, Jacqueline Deen
Format: Article
Language:English
Published: Taylor & Francis Group 2025-12-01
Series:Expert Review of Vaccines
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Online Access:https://www.tandfonline.com/doi/10.1080/14760584.2025.2539889
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author Kristal An Agrupis
Michelle Ylade
Yang Yang Qi
Maria Vinna Crisostomo
Jedas Veronica Daag
Gianne Lariz Magsakay
Jude Raphael Lo
Kiarah Louise Florendo
March Helena Jane Lopez
Jayne Marie Enriquez
Irish Lobitaña
Gretchen Bonita Ranada
Regina Alfonso
Mitzi Marie Chua
Mitzie Lou Osabel
Mary Ann Igoy-Bacay
Carren Anne Bocaling
Lorenz Von Seidlein
Xuanyi Wang
Jacqueline Deen
author_facet Kristal An Agrupis
Michelle Ylade
Yang Yang Qi
Maria Vinna Crisostomo
Jedas Veronica Daag
Gianne Lariz Magsakay
Jude Raphael Lo
Kiarah Louise Florendo
March Helena Jane Lopez
Jayne Marie Enriquez
Irish Lobitaña
Gretchen Bonita Ranada
Regina Alfonso
Mitzi Marie Chua
Mitzie Lou Osabel
Mary Ann Igoy-Bacay
Carren Anne Bocaling
Lorenz Von Seidlein
Xuanyi Wang
Jacqueline Deen
author_sort Kristal An Agrupis
collection DOAJ
description Background CoronaVac (Sinovac) was initially effective against symptomatic COVID-19 and severe outcomes, but its performance against the immune-evasive Omicron variant remains uncertain. This study evaluated the effectiveness of CoronaVac against hospitalized COVID-19 among Filipino adults during the Omicron-dominant wave.Research design and methods We conducted a test-negative case–control study from November 2022 to November 2023 in three tertiary government hospitals in the Philippines. Adults hospitalized with acute respiratory illness (ARI) were enrolled. Cases tested positive for SARS-CoV-2 by RT-PCR; controls tested negative. Vaccination status was confirmed via vaccination cards or the national registry. Conditional logistic regression estimated vaccine effectiveness (VE). Genomic sequencing identified circulating variants.Results Among 2,365 participants, 165 (7.0%) were COVID-19 positive. In an age-matched analysis (104 cases, 408 controls), two CoronaVac doses provided 61.3% protection (95% CI: 5.3–84.2%) against critical illness. A heterologous booster conferred 65.9% protection against severe disease, 90.1% against critical illness, and 60.5% against death. Sequencing of 23/46 samples confirmed Omicron XBB-like variants.Conclusion Two doses of CoronaVac offered moderate protection against severe COVID-19. Heterologous boosters significantly improved protection, especially against critical illness and death, supporting ongoing booster campaigns after inactivated vaccine priming.
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spelling doaj-art-aee86348f3cd4569a905c7ef679d0dcd2025-08-20T03:16:01ZengTaylor & Francis GroupExpert Review of Vaccines1476-05841744-83952025-12-0124173874910.1080/14760584.2025.2539889Effectiveness of CoronaVac primary series with and without booster against hospitalized COVID-19 during the Omicron-predominant epidemic wave in the Philippines: a test-negative case–control studyKristal An Agrupis0Michelle Ylade1Yang Yang Qi2Maria Vinna Crisostomo3Jedas Veronica Daag4Gianne Lariz Magsakay5Jude Raphael Lo6Kiarah Louise Florendo7March Helena Jane Lopez8Jayne Marie Enriquez9Irish Lobitaña10Gretchen Bonita Ranada11Regina Alfonso12Mitzi Marie Chua13Mitzie Lou Osabel14Mary Ann Igoy-Bacay15Carren Anne Bocaling16Lorenz Von Seidlein17Xuanyi Wang18Jacqueline Deen19Institute of Child Health and Human Development, National Institutes of Health, University of the Philippines Manila, Manila, PhilippinesInstitute of Child Health and Human Development, National Institutes of Health, University of the Philippines Manila, Manila, PhilippinesInstitutes of Biomedical Sciences, Shanghai Medical College, Fudan University, Shanghai, ChinaInstitute of Child Health and Human Development, National Institutes of Health, University of the Philippines Manila, Manila, PhilippinesInstitute of Child Health and Human Development, National Institutes of Health, University of the Philippines Manila, Manila, PhilippinesInstitute of Child Health and Human Development, National Institutes of Health, University of the Philippines Manila, Manila, PhilippinesInstitute of Child Health and Human Development, National Institutes of Health, University of the Philippines Manila, Manila, PhilippinesInstitute of Child Health and Human Development, National Institutes of Health, University of the Philippines Manila, Manila, PhilippinesInstitute of Child Health and Human Development, National Institutes of Health, University of the Philippines Manila, Manila, PhilippinesInstitute of Child Health and Human Development, National Institutes of Health, University of the Philippines Manila, Manila, PhilippinesInstitute of Child Health and Human Development, National Institutes of Health, University of the Philippines Manila, Manila, PhilippinesDepartment of Family and Community Medicine, Mariano Marcos Memorial Hospital & Medical Center, City of Batac, PhilippinesInfectious Disease Section, Department of Internal Medicine, Vicente Sotto Memorial Medical Center, Cebu, PhilippinesInfectious Disease Section, Department of Internal Medicine, Vicente Sotto Memorial Medical Center, Cebu, PhilippinesDepartment of Internal Medicine, Davao Regional Medical Center, Tagum City, PhilippinesVirology Department, Research Institute for Tropical Medicine, Alabang Muntinlupa City, PhilippinesVirology Department, Research Institute for Tropical Medicine, Alabang Muntinlupa City, PhilippinesMahidol-Oxford Tropical Medicine Research Unit, Bangkok, ThailandInstitutes of Biomedical Sciences, Shanghai Medical College, Fudan University, Shanghai, ChinaInstitute of Child Health and Human Development, National Institutes of Health, University of the Philippines Manila, Manila, PhilippinesBackground CoronaVac (Sinovac) was initially effective against symptomatic COVID-19 and severe outcomes, but its performance against the immune-evasive Omicron variant remains uncertain. This study evaluated the effectiveness of CoronaVac against hospitalized COVID-19 among Filipino adults during the Omicron-dominant wave.Research design and methods We conducted a test-negative case–control study from November 2022 to November 2023 in three tertiary government hospitals in the Philippines. Adults hospitalized with acute respiratory illness (ARI) were enrolled. Cases tested positive for SARS-CoV-2 by RT-PCR; controls tested negative. Vaccination status was confirmed via vaccination cards or the national registry. Conditional logistic regression estimated vaccine effectiveness (VE). Genomic sequencing identified circulating variants.Results Among 2,365 participants, 165 (7.0%) were COVID-19 positive. In an age-matched analysis (104 cases, 408 controls), two CoronaVac doses provided 61.3% protection (95% CI: 5.3–84.2%) against critical illness. A heterologous booster conferred 65.9% protection against severe disease, 90.1% against critical illness, and 60.5% against death. Sequencing of 23/46 samples confirmed Omicron XBB-like variants.Conclusion Two doses of CoronaVac offered moderate protection against severe COVID-19. Heterologous boosters significantly improved protection, especially against critical illness and death, supporting ongoing booster campaigns after inactivated vaccine priming.https://www.tandfonline.com/doi/10.1080/14760584.2025.2539889COVID-19CoronaVacSinovacinactivated vaccinesvaccine effectivenessSARS-CoV-2
spellingShingle Kristal An Agrupis
Michelle Ylade
Yang Yang Qi
Maria Vinna Crisostomo
Jedas Veronica Daag
Gianne Lariz Magsakay
Jude Raphael Lo
Kiarah Louise Florendo
March Helena Jane Lopez
Jayne Marie Enriquez
Irish Lobitaña
Gretchen Bonita Ranada
Regina Alfonso
Mitzi Marie Chua
Mitzie Lou Osabel
Mary Ann Igoy-Bacay
Carren Anne Bocaling
Lorenz Von Seidlein
Xuanyi Wang
Jacqueline Deen
Effectiveness of CoronaVac primary series with and without booster against hospitalized COVID-19 during the Omicron-predominant epidemic wave in the Philippines: a test-negative case–control study
Expert Review of Vaccines
COVID-19
CoronaVac
Sinovac
inactivated vaccines
vaccine effectiveness
SARS-CoV-2
title Effectiveness of CoronaVac primary series with and without booster against hospitalized COVID-19 during the Omicron-predominant epidemic wave in the Philippines: a test-negative case–control study
title_full Effectiveness of CoronaVac primary series with and without booster against hospitalized COVID-19 during the Omicron-predominant epidemic wave in the Philippines: a test-negative case–control study
title_fullStr Effectiveness of CoronaVac primary series with and without booster against hospitalized COVID-19 during the Omicron-predominant epidemic wave in the Philippines: a test-negative case–control study
title_full_unstemmed Effectiveness of CoronaVac primary series with and without booster against hospitalized COVID-19 during the Omicron-predominant epidemic wave in the Philippines: a test-negative case–control study
title_short Effectiveness of CoronaVac primary series with and without booster against hospitalized COVID-19 during the Omicron-predominant epidemic wave in the Philippines: a test-negative case–control study
title_sort effectiveness of coronavac primary series with and without booster against hospitalized covid 19 during the omicron predominant epidemic wave in the philippines a test negative case control study
topic COVID-19
CoronaVac
Sinovac
inactivated vaccines
vaccine effectiveness
SARS-CoV-2
url https://www.tandfonline.com/doi/10.1080/14760584.2025.2539889
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