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. 2022 Jul;16(4):673-679.
doi: 10.1111/irv.12973. Epub 2022 Feb 15.

Vaccine effectiveness against COVID-19 among symptomatic persons aged ≥12 years with reported contact with COVID-19 cases, February-September 2021

Jessie R Chung  1 , Sara S Kim  1 , Edward A Belongia  2 , Huong Q McLean  2 , Jennifer P King  2 , Mary Patricia Nowalk  3 , Richard K Zimmerman  3 , Krissy Moehling Geffel  3 , Emily T Martin  4 , Arnold S Monto  4 , Lois E Lamerato  5 , Manjusha Gaglani  6   7 , Eric Hoffman  6 , Marcus Volz  6 , Michael L Jackson  8 , Lisa A Jackson  8 , Manish M Patel  1 , Brendan Flannery  1
Affiliations

Vaccine effectiveness against COVID-19 among symptomatic persons aged ≥12 years with reported contact with COVID-19 cases, February-September 2021

Jessie R Chung et al. Influenza Other Respir Viruses. 2022 Jul.

Abstract

Background: Individuals in contact with persons with COVID-19 are at high risk of developing COVID-19; protection offered by COVID-19 vaccines in the context of known exposure is poorly understood.

Methods: Symptomatic outpatients aged ≥12 years reporting acute onset of COVID-19-like illness and tested for SARS-CoV-2 between February 1 and September 30, 2021 were enrolled. Participants were stratified by self-report of having known contact with a COVID-19 case in the 14 days prior to illness onset. Vaccine effectiveness was evaluated using the test-negative study design and multivariable logistic regression.

Results: Among 2229 participants, 283/451 (63%) of those reporting contact and 331/1778 (19%) without known contact tested SARS-CoV-2-positive. Adjusted vaccine effectiveness was 71% (95% confidence interval [CI], 49%-83%) among fully vaccinated participants reporting a known contact versus 80% (95% CI, 72%-86%) among those with no known contact (p-value for interaction = 0.2).

Conclusions: This study contributes to growing evidence of the benefits of vaccinations in preventing COVID-19 and support vaccination recommendations and the importance of efforts to increase vaccination coverage.

Keywords: COVID-19; SARS-CoV-2; vaccine effectiveness.

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Figures

FIGURE 1
FIGURE 1
Estimates of vaccine effectivenessa against laboratory‐confirmed symptomatic COVID‐19 among participants with and without reported known contact with persons with COVID‐19 during the 14 days before illness onset, US Flu VE Network, February 1 to September 30, 2021. CI, confidence interval. aVaccine effectiveness (VE) of full vaccination by documented records versus unvaccinated. Model adjusted for study site, age in years (continuous), enrollment period (natural cubic spline with 3 percentile knots of interval between January 1, 2021 and illness onset date), and self‐reported race/ethnicity
See this image and copyright information in PMC

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