Vaccine Effectiveness During Outbreak of COVID-19 Alpha (B.1.1.7) Variant in Men's Correctional Facility, United States

Rachel A. Silverman; Alessandro Ceci; Alasdair Cohen; Meagan Helmick; Erica Short; Paige Bordwine; Michael J. Friedlander; Carla V. Finkielstein


Emerging Infectious Diseases. 2022;28(7):1313-1320. 

In This Article

Abstract and Introduction


In April 2021, a COVID-19 outbreak occurred at a correctional facility in rural Virginia, USA. Eighty-four infections were identified among 854 incarcerated persons by facilitywide testing with reverse transcription quantitative PCR (qRT-PCR). We used whole-genome sequencing to link all infections to 2 employees infected with the B.1.1.7α (UK) variant. The relative risk comparing unvaccinated to fully vaccinated persons (mRNA-1273 [Moderna,]) was 7.8 (95% CI 4.8–12.7), corresponding to a vaccine effectiveness of 87.1% (95% CI 79.0%–92.1%). Average qRT-PCR cycle threshold values were lower, suggesting higher viral loads, among unvaccinated infected than vaccinated cases for the nucleocapsid, envelope, and spike genes. Vaccination was highly effective at preventing SARS-CoV-2 infection in this high-risk setting. This approach can be applied to similar settings to estimate vaccine effectiveness as variants emerge to guide public health strategies during the ongoing pandemic.


Incarcerated populations are especially vulnerable to communicable disease spread, including SARS-CoV-2, the virus responsible for COVID-19.[1–3] Outbreaks in correctional facilities have been linked to outbreaks and disease spread in the wider community.[4,5] Although incarcerated persons and correctional staff were recommended as a priority group to receive vaccination,[6] reported willingness among employees and incarcerated persons to receive COVID-19 vaccines was lower than among the general population.[7] Thus, outbreaks in prisons present a valuable opportunity to assess vaccine effectiveness in a real-world, high-risk environment.