PURPOSE:

• Wang et al. (JAMA, 2020) assessed whether a program of universal masking in a large healthcare system was associated with the SARS-CoV-2 infection rate among healthcare personnel

METHODS:

• Retrospective cohort study
  • Mass General Brigham (MGB) |12 hospitals 75 000 employees
• Hospital system initiated a COVID-19 infection reduction strategy that included
  • Systematic SARS-CoV-2 testing of symptomatic healthcare personnel
  •  Universal masking of all healthcare personnel and patients (surgical masks)
• 3 phases
  • Preintervention period before universal masking: March 1 to 24, 2020
  • Transition period until implementation of universal masking of patients: March 25 to April 5, 2020
    • Lag period to allow for manifestations of symptoms: April 6 to 10, 2020
  • Intervention period; April 11 to 30, 2020
• Positivity rate
  • Numerator: First positive test result for all healthcare personnel
  • Denominator: Healthcare personnel who never tested positive plus those who tested positive that day
• Statistical analysis
  • Mean trends calculated based on overall slope of each period was calculated using linear regression
  • Change in overall slope compared between the preintervention vs intervention periods

RESULTS:

• 9850 Healthcare Personnel underwent testing
  • Positive results: 12.9% | Median age, 39 years
    • 73% female | 7.4% physicians or trainees | 26.5% nurses or PAs | 17.8% technologists or nursing support | 48.3% other
  • Preintervention period: SARS-CoV-2 positivity rate increased exponentially from 0% to 21.32% | Weighted mean increase of 1.16% per day | Case doubling time of 3.6 days (95% CI, 3.0 to 4.5 days)
  • Intervention period: SARS-CoV-2 positivity rate decreased linearly from 14.65% to 11.46% | Weighted mean decline of 0.49% per day
  • Net slope change: 1.65% more decline per day compared with the preintervention period (95% CI, 1.13% to 2.15%; P < .001)

CONCLUSION:

• Universal masking was associated with a decrease in SARS-CoV-2 infection rates among healthcare personnel
• The authors acknowledge the possibility of confounding due to other transmission prevention measures such as social distancing
• The authors state that

Randomized trials of universal masking of HCWs during a pandemic are likely not feasible

Nonetheless, these results support universal masking as part of a multipronged infection reduction strategy in health care settings

Learn More – Primary Sources:

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

Related ObG Topics:

COVID-19, PPE and Second Stage of Labor: Current US Guidance

Surgical Masks Reduce Viral Shedding

ACOG COVID-19 FAQs for Obstetrical Care

NIH COVID-19 Treatment Guidelines