ABSTRACT
Introduction/ Background: During September-October 2020, an outbreak of COVID-19 occurred at Masaka Ssaza, a COVID-19 quarantine prison (holding center for newlysentenced persons before transit to their host prison) in Central Uganda. We investigated to identify factors associated with introduction and spread of infection in Masaka Ssaza prison. Methods: We defined a case as PCR-confirmed SARS-CoV-2 infection in a prisoner/staff at Masaka Ssaza prison during September- October 2020. A control was defined as a prisoner or staff at Masaka Ssaza with a negative test during the same timeframe. We reviewed prison medical records to identify casepatients and interviewed prison staff to understand possible avenues of introduction of infection and opportunities for spread. We conducted a casecontrol study interviewing prisoners and staff to determine factors associated with spread of the infection. Logistic regression was used to assess factors associated with infection. Results: The index case was Inmate A, a 33-year-old male who entered the prison on September 16, 2020. On September 23, Inmate A learned that a colleague with whom he had close contact before imprisonment had died of COVID-19 which he reported to the warden leading to mass testing. The overall attack rate was 40/100. Ward-specific prisoner density ranged from 0.3-2.1 prisoners/square meter. Face mask ownership among case-patients was 35%. Using a face mask all the time was protective (aOR= 0.03: 95% CI 0.01- 0.09). Residing in Ward 6 was associated with increased odds of infection (aOR=7.4;95% CI 1.6- 3.4). Impact: Consistent use of face masks was protective. Unrestricted access to handwashing facilities, facemask use, and strict adherence to 'do not enter another ward' rules could mitigate risk of future outbreaks. Conclusion: COVID-19 was likely introduced into Masaka Ssaza prison by an infected incoming prisoner. The outbreak may have been amplified by congestion in wards and at mealtimes and low use of preventive measures.