Alliance for Pandemic Preparedness

July 15, 2020

Association Between Universal Masking in a Health Care System and SARS-CoV-2 Positivity Among Health Care Workers

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  • Among 9,850 health care workers Massachusetts between March 1 and April 30, 2020 13% were positive for SARS-CoV-2 by RT-PCR. Prior to implementation of universal masking (March 1-24, 2020), the SARS-CoV-2 positivity rate increased exponentially from 0% to 21%, with a case doubling time of 3.6 days (95%CI 3.0-4.5 days). After implementation of universal masking (April 11-30, 2020), the positivity rate decreased linearly from 14.7% to 11.5%, with a weighted mean decline of 0.49% per day. 

Wang et al. (July 14, 2020). Association Between Universal Masking in a Health Care System and SARS-CoV-2 Positivity Among Health Care Workers. JAMA. https://doi.org/10.1001/jama.2020.12897