Non-pharmaceutical infection prevention measures in nosocomial SARS-CoV-2 outbreaks: a retrospective multi-centre cohort study

Background

Hospital severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreaks are relevant for patients and healthcare systems within and beyond the pandemic.

Aim

To explore the characteristics of SARS-CoV-2 outbreaks and their infection prevention and control (IPC) measures during the different pandemic waves.

Methods

A comprehensive structured template for SARS-CoV-2 outbreaks was developed and filled out by six university hospitals. The main outcome variable was outbreak size (OS).

Findings

A total of 80 outbreaks and 734 infection cases were enrolled between March 2020 and February 2023. In the majority of outbreaks (85%) a contact tracing (CT) team was in place. In 13 (16%) outbreaks the CT team was exclusively responsible for CT, which was negatively linked to OS when adjusting for SARS-CoV-2 waves (estimate (β) = –1.350; standard error (SE) = 0.274; P < 0.0001). Patients as index had a greater association with OS than healthcare workers (HCWs) (β = –0.29; SE = 0.098; P = 0.003). Additionally, the mandatory use of face masks by patients in the presence of HCWs was negatively linked to OS (β = –0.237; SE = 0.08; P = 0.003). The frequency of patient screening during outbreaks varied considerably, whereby higher frequency screenings for SARS-CoV-2 were negatively associated with OS (β = –0.358; SE = 0.109; P = 0.001).

Conclusion

Our data provide insights in non-pharmaceutical outbreak prevention and management, revealing that the mandatory use of face masks by patients in the presence of HCWs and a high patient screening frequency in ongoing outbreaks were significantly associated with smaller outbreaks. Further studies are required to allow for generalizability.