Top 5 Takeaways

1. High Attack Rate: 74% of incarcerated persons in two housing units were infected during the outbreak.
2. Vaccination Impact: The attack rate was higher among unvaccinated persons (93%) compared to fully vaccinated persons (70%).
3. Hospitalizations and Deaths: Three of the four hospitalizations and the only death occurred among unvaccinated persons.
4. Vaccine Efficacy: The Pfizer-BioNTech vaccine recipients had higher attack rates compared to Moderna recipients, especially among those vaccinated ≥4 months before the outbreak.
5. Prevention Strategies: Despite high vaccination coverage, multiple COVID-19 prevention strategies are critical in congregate settings to limit transmission.

Original Article Author and Citation

Corresponding Author

Liesl M. Hagan, vqf8@cdc.gov

Suggested Citation

Hagan LM, McCormick DW, Lee C, et al. Outbreak of SARS-CoV-2 B.1.617.2 (Delta) Variant Infections Among Incarcerated Persons in a Federal Prison — Texas, July–August 2021. MMWR Morb Mortal Wkly Rep 2021;70:1349–1354. DOI: http://dx.doi.org/10.15585/mmwr.mm7038e3

Summary

In July 2021, a COVID-19 outbreak involving the Delta variant occurred in a federal prison in Texas, affecting 172 of 233 incarcerated persons. The attack rate was significantly higher among unvaccinated persons compared to vaccinated ones. The outbreak highlighted the importance of vaccination and the need for multiple prevention strategies in congregate settings to limit the spread of SARS-CoV-2.

Methods

The CDC and the Federal Bureau of Prisons (BOP) investigated the outbreak by analyzing data on infection status, symptom onset, hospitalizations, and deaths. Testing included rapid antigen tests and RT-PCR, with a subset of participants undergoing serial swabbing and viral culture attempts. Statistical analyses were performed to compare attack rates and outcomes based on vaccination status and other factors.

Discussion

The study demonstrated that despite high vaccination coverage, the Delta variant could cause significant outbreaks in congregate settings. Vaccinated individuals had lower rates of severe illness and death, underscoring the importance of vaccination. However, the presence of infectious virus in both vaccinated and unvaccinated persons highlighted the need for continued preventive measures.

Conclusion

Widespread vaccination, along with other preventive strategies such as early diagnostic testing, screening, medical isolation, quarantine, masking, and physical distancing, remain crucial in limiting SARS-CoV-2 transmission and related illnesses in correctional facilities.

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