Observational studyPloS one2024
Effectiveness of ChAdOx1 nCoV-19 and BBIBP-CorV vaccines against COVID-19-associated hospitalisation and death in the Seychelles infected adult population.
Observational study in PloS one, 2024. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 2 papers, 1 of them a synthesis that pooled it.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
2 citing papers in PubMed, 1 synthesis or guideline pooled it, 2 citations in OpenAlex.
- Neutralising antibodies and protection from progression to severe COVID-19: A meta-analysis.PLoS medicine · 2026Pooled it
- The effectiveness of COVID-19 vaccination in preventing hospitalisation and mortality: A nationwide cross-sectional study in Iran.Journal of global health · 2024Article
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
6 authors at 2 institutions in 2 countries.
Funding
No grant is acknowledged in the PubMed record.
Abstract
backgroundThe Seychelles COVID-19 vaccination campaign was initiated using two different vaccines during the first wave of the pandemic in 2021. This observational study estimated vaccine effectiveness against severe outcomes (hospitalisation and/or death) from individuals infected with COVID-19 in the Seychelles adult population during Beta and Delta variant transmission.
methodsThis nationwide retrospective cohort study included all Seychellois residents aged ≥ 18 years who tested positive by RT-PCR or rapid antigen test for COVID-19 between January 25, 2021, and June 30, 2021. We measured the relative risk (RR) of laboratory-confirmed SARS-CoV-2 hospitalisation and/or death among individuals partially or fully vaccinated with ChAdOx1 nCoV-19 (SII Covishield) or BBIBP-CorV (Sinopharm) vaccines compared to unvaccinated individuals using modified Poisson regression. Controlling for age, gender and calendar month, vaccine effectiveness was estimated as 1-RR ≥14 days after the first dose and ≥7 days after the second dose for each available vaccine versus an unvaccinated control group.
resultsA total of 12,326 COVID-19 infections were reported in adult Seychellois residents between January 25, 2021, and June 30, 2021. Of these, 1,287 individuals received one dose of either BBIBP-CorV (Sinopharm) or ChAdOx1-nCoV-19 (SII Covishield) vaccine, and 5,225 individuals received two doses. Estimated adjusted effectiveness of two doses of either Sinopharm or SII Covishield was high, at 70% (95% CI 58%-78%) and 71% (95% CI 62%-78%) respectively. Sinopharm maintained high levels of protection against severe outcomes in partially vaccinated individuals at 61% (95% CI 36%-76%), while the effectiveness of one dose of SII Covishield was low at 29% (95% CI 1%-49%).
conclusionsThis observational study demonstrated high levels of protection of two doses of two vaccine types against severe outcomes of COVID-19 during the first wave of the pandemic driven by Beta (B.1.351) and Delta (B.1.617.2) variant predominance. One dose of ChAdOx1-nCoV-19 (Covishield SII) was found to be inadequate in protecting the general adult population against hospitalisation and/or death from COVID-19.
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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.