Modelling mass asymptomatic testing strategies for early containment of infectious disease outbreaks in prisons

Objective: Investigate a strategy of mass asymptomatic testing and isolation ("pulse testing") aimed at early containment of outbreaks in prisons in comparison to or combination with a symptom-based isolation strategy. Methods: Simulations using an individual-based time-since-infection model were run under different pathogen and intervention strategy scenarios. Measured outcomes were the proportion of outbreaks contained and number of individuals isolated. Results: For R0 = 2, 25% probability of being asymptomatic (pa = 0.25), a COVID-19-like infection dynamics and perfect adherence, one pulse test contained approximately 20% of outbreaks, and three tests up to 50%. With no asymptomatic cases, three tests performed similarly to isolating cases one day after symptoms (approx 55% outbreaks contained), but symptom-based isolation degraded significantly faster than pulse testing with increasing pa. With perfect adherence, combining both interventions contained between approx 25% (R0 = 3, pa = 0.5) and > 90% (R0 = 1.5, pa = 0) of outbreaks. Across all scenarios, pulse testing isolated substantially fewer individuals than symptom-based isolation, e.g. approx 5% versus approx 30% for R0 = 2 and pa = 0.25. Conclusion: If implemented promptly upon outbreak declaration and with high adherence, pulse testing may stop outbreaks early, substantially reducing the number of isolations and mitigating the impact on prison regime and resident/staff wellbeing. However, for large R0 or delayed implementation, effectiveness drops rapidly.