Trial reportScientific reports2026
Indirect protection and long-term effectiveness of inactivated COVID-19 vaccine: a stepped-wedge randomised trial in Serrana, Brazil.
Trial report in Scientific reports, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 1 paper.
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
1 citing paper in PubMed.
- Demographic and socioeconomic characteristics associated with SARS-CoV-2 reinfection: An observational study.PLOS global public health · 2026Article
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
25 authors.
Funding
Abstract
Currently approved vaccines have shown wide ranges of estimated efficacy. Despite the well-known benefits of inactivated virus vaccines, little information on their effectiveness has been robustly provided to monitor their specific impact. A stepped-wedge trial is an approach for assessing vaccine effectiveness and indirect protection in the real world. By the end of the study, all participants can receive the intervention, eliminating the ethical dilemma of placebo, especially during a pandemic. The aim of this study was to assess the effectiveness of an inactivated COVID-19 vaccine in a massive urban population during the uncontrolled COVID-19 epidemic. We evaluated the long-term vaccine effectiveness (VE) of CoronaVac in Serrana, Brazil, using a stepped-wedge randomised trial. An indirect effect was also inferred from the temporal association between increasing vaccine coverage and the concurrent decline in SARS-CoV-2 incidence among participants who were not yet fully vaccinated. The city was divided into 25 subareas, clustered into four groups, and randomised to receive CoronaVac in a two-dose scheme. After 6 months, a booster dose was offered by the Brazilian Immunization Program. Participants were followed for one year, divided into four periods: February-May 2021; May-August 2021; August-November 2021; November 2021-February 2022. Vaccination occurred between February 14 and April 11, 2021. Up to 27,390 participants received the CoronaVac first dose, corresponding to 82.8% of the adult urban population. In the 1
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