Effect of a national policy of universal masking and uniform criteria for severe acute respiratory coronavirus virus 2 (SARS-CoV-2) exposure on hospital staff infection and quarantine.

OBJECTIVE

To determine the effect of 2 regulations issued by the Israel Ministry of Health on coronavirus disease 2019 (COVID-19) infections and quarantine among healthcare workers (HCWs) in general hospitals.

DESIGN

Before-and-after intervention study without a control group (interrupted time-series analysis).

SETTING

All 29 Israeli general hospitals.

PARTICIPANTS

All HCWs.

INTERVENTIONS

Two national regulations were issued on March 25, 2020: one required universal masking of HCWs, patients, and visitors in general hospitals and the second defined what constitutes HCW exposure to severe acute respiratory coronavirus virus 2 (SARS-CoV-2) and when quarantine is required.

RESULTS

Overall, 283 HCWs were infected at work or from an unknown source. Before the intervention, the number of HCWs infected at work increased by 0.5 per day (95% confidence interval [CI], 0.2-0.7; < .001), peaking at 16. After the intervention, new infections declined by 0.2 per day (95% CI, -0.3 to -0.1; < .001). Before the intervention, the number of HCWs in quarantine or isolation increased by 97 per day (95% CI, 90-104; < .001), peaking at 2,444. After the intervention, prevalence decreased by 59 per day (95% CI, -72 to -46; < .001). Epidemiological investigations determined that the most common source of HCW infection (58%) was a coworker.

CONCLUSIONS

Universal masking in general hospitals reduced the risk of hospital-acquired COVID-19 among HCWs. Universal masking combined with uniform definitions of HCW exposure and criteria for quarantine limited the absence of HCWs from the workforce.