Rapid antigen testing as a reactive public health response to surges in SARS-CoV-2 outbreak risk in healthcare settings

Abstract Background Surges in community SARS-CoV-2 incidence increase risk of importation and subsequent transmission in healthcare facilities. Antigen rapid diagnostic testing (Ag-RDT) is widely used for population screening, but its health and economic benefits as a reactive intervention in healthcare settings are unclear. Methods We used stochastic, individual-based modelling to simulate SARS-CoV-2 transmission in a long-term care facility with varying COVID-19 containment measures in place (social distancing, face masks, vaccination). In contrast to routine symptomatic testing using reverse-transcriptase polymerase chain reaction (RT-PCR), we evaluated the efficacy and health-economic efficiency of single or repeated population-wide Ag-RDT screening interventions implemented in response to surges in nosocomial outbreak risk. Results Depending on the baseline containment measures in place, nosocomial SARS-CoV-2 incidence was reduced by up to 40-47% (range of means) with routine RT-PCR testing, 59-63% with the addition of a timely round of Ag-RDT screening, and 69-75% with well-timed two-round screening. For the latter, a delay of 4 to 5 days between the first and second rounds was optimal for transmission prevention. Efficacy varied depending on test sensitivity, subpopulations targeted, and SARS-CoV-2 incidence in the community. Efficiency, however, varied primarily depending on the other containment measures in place: surveillance costs for a combined strategy of routine RT-PCR testing and reactive Ag-RDT screening ranged from a mean €420-€10,260/infection averted across scenarios (default unit costs: €5/Ag-RDT test, €50/RT-PCR test). Interpretation Reactive Ag-RDT screening complements routine RT-PCR testing, and systematic two-round screening helps overcome limited, time-varying diagnostic sensitivity. Health-economic gains scale significantly with underlying nosocomial outbreak risk. Funding National Research Agency, Canadian Institutes of Health Research, Fondation de France