Investigation of a COVID-19 outbreak at a regional prison, Northern Uganda, September 2020.

Despite implementing measures to prevent introduction of COVID-19 in prisons, a COVID-19 outbreak occurred at Moroto Prison, northern Uganda in September 2020. We investigated factors associated with the introduction and spread of COVID-19 in the prison. A case was PCR-confirmed SARS-CoV-2 infection in a prisoner/staff at Moroto Prison during August-September 2020. We reviewed prison medical records to identify case-patients and interviewed prison and hospital staff to understand possible infection mechanisms for the index case-patient and opportunities for spread. In a retrospective cohort study, we interviewed all prisoners and available staff to identify risk factors. Data were analyzed using log-binomial regression. On September 1, 2020, a recently-hospitalized prisoner with unrecognized SARS-CoV-2 infection was admitted to Moroto Prison quarantine. He had become infected while sharing a hospital ward with a subsequently-diagnosed COVID-19 patient. A sample taken from the hospitalized prisoner on August 20 tested positive on September 3. Mass reactive testing at the prison on September 6, 14, and 15 revealed infection among 202/692 prisoners and 8/90 staff (overall attack rate=27%). One prison staff and one prisoner who cared for the sick prisoner while at the hospital re-entered the main prison without quarantining. Both tested positive on September 6. Food and cleaning service providers also regularly transited between quarantine and unrestricted prison areas. Using facemasks >50% of the time (adjusted risk ratio [aRR]=0.26; 95%CI: 0.13-0.54), or in combination with handwashing after touching surfaces (aRR=0.25; 95%CI: 0.14-0.46) were protective. Prisoners recently transferred from other facilities to Moroto Prison had an increased risk of infection (aRR=1.50; 95%CI: 1.02-2.22). COVID-19 was likely introduced into Moroto Prison quarantine by a prisoner with hospital-acquired infection and delayed test results, and/or by caretakers who were not quarantined after hospital exposures. The outbreak may have amplified via shared food/cleaning service providers who transited between quarantined and non-quarantined prisoners. Facemasks and handwashing were protective. Reduced test turnaround time for the hospitalized prisoner could have averted this outbreak. Testing incoming prisoners for SARS-CoV-2 before quarantine, providing unrestricted soap/water for handwashing, and universal facemask use in prisons could mitigate risk of future outbreaks.