ArticleClinical microbiology and infection : the official publication of the European Society of Clinical Microbiology and Infectious Diseases2023
Vaccine effectiveness against Delta, Omicron BA.1, and BA.2 in a highly vaccinated Asian setting: a test-negative design study.
Article in Clinical microbiology and infection : the official publication of the European Society of Clinical Microbiology and Infectious Diseases, 2023. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 14 papers, 1 of them a synthesis that pooled it.
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Who cites it
14 citing papers in PubMed, 1 synthesis or guideline pooled it, 32 citations in OpenAlex.
- COVID-19 Vaccine Effectiveness of Booster Doses Against Delta and Omicron Variants Over Follow-up Times Using Longitudinal Meta-analysis.Journal of research in health sciences · 2024Pooled it
- Characterization of post-acute multi-organ sequelae following SARS-CoV-2 Infection in the Delta and Omicron Eras in a highly boosted population.BMC global and public health · 2026Article
- Multi-systemic risk of post-acute sequelae associated with SARS-CoV-2 reinfection.BMC global and public health · 2025Article
- Real-World Effectiveness of Boosting Against Omicron Hospitalization in Older Adults, Stratified by Frailty.Vaccines · 2025Article
- Intensity of public health and social measures are associated with effectiveness of SARS-CoV-2 vaccine in test-negative study.medRxiv : the preprint server for health sciences · 2025Article
- Potential biases in test-negative design studies of COVID-19 vaccine effectiveness arising from the inclusion of asymptomatic individuals.American journal of epidemiology · 2025Article
- Differences in virus and immune dynamics for SARS-CoV-2 Delta and Omicron infections by age and vaccination histories.BMC infectious diseases · 2024Article
- Durable cross-protective neutralizing antibody responses elicited by lipid nanoparticle-formulated SARS-CoV-2 mRNA vaccines.NPJ vaccines · 2024Article
- Factors associated with delayed diagnosis of symptomatic adult COVID-19 cases presenting to primary care: a population-wide study during transition from Delta to Omicron BA.1 in Singapore.The Lancet regional health. Western Pacific · 2023Article
- Protection of homologous and heterologous boosters after primary schemes of rAd26-rAd5, ChAdOx1 nCoV-19 and BBIBP-CorV during the omicron outbreak in adults of 50 years and older in Argentina: a test-negative case-control study.Lancet regional health. Americas · 2023Article
- Vaccine effectiveness against COVID-19 hospitalisation in adults (≥ 20 years) during Omicron-dominant circulation: I-MOVE-COVID-19 and VEBIS SARI VE networks, Europe, 2021 to 2022.Euro surveillance : bulletin Europeen sur les maladies transmissibles = European communicable disease bulletin · 2023Article
- Protective immunity of SARS-CoV-2 infection and vaccines against medically attended symptomatic omicron BA.4, BA.5, and XBB reinfections in Singapore: a national cohort study.The Lancet. Infectious diseases · 2023Article
- Relative role of community transmission and campus contagion in driving the spread of SARS-CoV-2: Lessons from Princeton University.PNAS nexus · 2023Article
- BNT162b2 vaccine protection against omicron and effect of previous infection variant and vaccination sequence among children and adolescents in Singapore: a population-based cohort study.The Lancet. Child & adolescent health · 2023Article
Corrections and comments
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Authors and funding
7 authors at 3 institutions in 1 country.
Funding
No grant is acknowledged in the PubMed record.
Abstract
objectivesWe compared the vaccine effectiveness over time of the primary series and booster against infection and severe disease with the Delta, Omicron BA.1, and BA.2 variants in Singapore, an Asian setting with high vaccination coverage.
methodsWe conducted a test-negative case-control study on all adult residents in Singapore who underwent PCR testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in acute hospitals. Individuals with a negative PCR from 1 September, 2021, to 30 November, 2021, and 1 December, 2021, to 25 April, 2022, served as controls for the Delta and Omicron variants respectively, and PCR-positive individuals within these two time periods served as cases. Associations between vaccination status and SARS-CoV-2 infection and severe disease with the Delta or Omicron variants were measured using Poisson regressions. Vaccine effectiveness was calculated by taking 1 minus risk ratio.
resultsThere were 68 114 individuals comprising 58 495 controls and 9619 cases for the Delta period, of whom 53 093 completed the primary series and 9161 were boosted. For the Omicron period, 104 601 individuals comprising 80 428 controls, 8643 BA.1 cases, and 15 530 BA.2 cases were included, of whom 29 183 and 71 513 were vaccinated with the primary series and boosted, respectively. The primary series provided greater protection against infection with Delta (45%, 95% CI 40-50%) than against infection with Omicron (21%, 95% CI 7-34% for BA.1; 18%, 95% CI 6-29% for BA.2) at <2 months from vaccination. Vaccine effectiveness of the booster was similar against infection with BA.1 (44%, 95% CI 38-50%) and BA.2 (40%, 95% CI 35-40%). Protection against severe disease by the booster for BA.1 (83%, 95% CI 76-88%) and BA.2 (78%, 95% CI 73-82%) was comparable to that by the primary series for Delta (80%, 95% CI 73-85%).
conclusionOur findings support the use of a booster dose to reduce the risk of severe disease and mitigate the impact on the healthcare system in an Omicron-predominant epidemic.
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