One-dose ChAdOx1 nCoV-19 Vaccine Effectiveness Against Symptomatic COVID-19 in a vulnerable community in Rio de Janeiro, Brazil: test-negative design study

Ranzani, Otávio T.; Silva, Amanda A B; Peres, Igor Tona; Antunes, Bianca Brandão de Paula; Gonzaga-da-Silva, Thiago W.; Soranz, Daniel; Cerbino-Neto, José; Hamacher, Śılvio; Bozza, Fernando A.

doi:10.1101/2021.10.16.21265095

2021

DOI: 10.1101/2021.10.16.21265095

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One-dose ChAdOx1 nCoV-19 Vaccine Effectiveness Against Symptomatic COVID-19 in a vulnerable community in Rio de Janeiro, Brazil: test-negative design study

Otávio T. Ranzani

Amanda A B Silva

Igor Tona Peres

et al.

Abstract: We conducted a test-negative study design at the community “Complexo da Maré”, the largest group of favelas in Rio de Janeiro, Brazil, when Gamma and Delta were the predominant variants circulating. We estimated 42.4% (95% CI, 24.6, 56.0) protection against symptomatic COVID-19 after 21 days of one dose of ChAdOx1.

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Cited by 2 publications

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A systematic review of COVID-19 vaccine efficacy and effectiveness against SARS-CoV-2 infection and disease

Higdon

Wahl

Jones

et al. 2021

Preprint

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Billions of doses of COVID-19 vaccines have been administered around the world, dramatically reducing SARS-CoV-2 incidence in some settings. Many studies suggest vaccines provide a high degree of protection against infection and disease, but precise estimates vary and studies differ in design, outcomes measured, dosing regime, location, and circulating virus strains. Here we conduct a systematic review of COVID-19 vaccines as of August 2021. We included efficacy data from Phase 3 clinical trials for 13 vaccines within the WHO Emergency Use Listing evaluation process and real-world effectiveness for 5 vaccines with observational studies meeting inclusion criteria. Vaccine metrics collected include effects against asymptomatic infection, any infection, symptomatic COVID-19, and severe outcomes including hospitalization and death, for both partial and complete vaccination, and against SARS-CoV-2 variants of concern. In addition, we review the epidemiological principles behind the design and interpretation of vaccine effects, and explain important sources of heterogeneity between studies.

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A systematic review of COVID-19 vaccine efficacy and effectiveness against SARS-CoV-2 infection and disease

Higdon

Wahl

Jones

et al. 2021

Preprint

View full text Add to dashboard Cite

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Prior infections and effectiveness of SARS-CoV-2 vaccine in test-negative study: A systematic review and meta-analysis

Tsang

Sullivan

Huang

et al. 2022

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Background: Prior infection with SARS-CoV-2 can provide protection against infection and severe COVID-19. In settings with high pre-existing immunity, vaccine effectiveness (VE) should decrease with higher levels of immunity among unvaccinated individuals. Here, we conducted a systematic review and meta-analysis to understand the influence of prior infection on VE. Methods: We included test-negative design (TND) studies that examined VE against infection or severe disease (hospitalization, ICU admission, or death) for primary vaccination series. To determine the impact of prior infections on VE estimates, we compared studies that excluded or included people with prior COVID-19 infection. We also compared VE estimates by the cumulative incidence of cases before the start of and incidence rates during each study in the study locations, as further measures of prior infections in the community. Findings: We identified 67 studies that met inclusion criteria. Pooled VE among studies that included people with prior COVID-19 infection was lower against infection (pooled VE: 77%; 95% confidence interval (CI): 72%, 81%) and severe disease (pooled VE: 86%; 95% CI: 83%, 89%), compared with studies that excluded people with prior COVID-19 infection (pooled VE against infection: 87%; 95% CI: 85%, 89%; pooled VE against severe disease: 93%; 95% CI: 91%, 95%). There was a negative correlation between the cumulative incidence of cases before the start of the study and VE estimates against infection (spearman correlation (ρ) = -0.32; 95% CI: -0.45, -0.18) and severe disease (ρ = -0.49; 95% CI: -0.64, -0.30). There was also a negative correlation between the incidence rates of cases during the study period and VE estimates against infection (ρ = -0.48; 95% CI: -0.59, -0.34) and severe disease (ρ = -0.42; 95% CI: -0.58, -0.23). Interpretation: Based on a review of published VE estimates we found clear empirical evidence that higher levels of pre-existing immunity in a population were associated with lower VE estimates. Excluding previously infected individuals from VE studies may result in higher VE estimates with limited generalisability to the wider population. Prior infections should be treated as confounder and effect modificatory when the policies were targeted to whole population or stratified by infection history, respectively.

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One-dose ChAdOx1 nCoV-19 Vaccine Effectiveness Against Symptomatic COVID-19 in a vulnerable community in Rio de Janeiro, Brazil: test-negative design study

Cited by 2 publications

References 10 publications

A systematic review of COVID-19 vaccine efficacy and effectiveness against SARS-CoV-2 infection and disease

A systematic review of COVID-19 vaccine efficacy and effectiveness against SARS-CoV-2 infection and disease

Prior infections and effectiveness of SARS-CoV-2 vaccine in test-negative study: A systematic review and meta-analysis

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