MINIMAL REQUIRED EFFECTIVENESS AND COMPLIANCE OF SURGICAL MASKS AND RESPIRATORS TO MITIGATE AN INFLUENZA A PANDEMIC

Purpose: An influenza pandemic is one of the primary international public health concerns of the 21st century, and expenditures for influenza preparedness have reached $6 billion in the United States. Many countries are stockpiling surgical masks and N-95 respirators, and masks were widely distributed in Mexico during the recent outbreak of novel A influenza (H1N1). However, the effectiveness and cost-effectiveness of masks and respirators to reduce morbidity and mortality from pandemic influenza are unknown.

Method:   We developed a dynamic transmission model of pandemic influenza A in a U.S. metropolitan city to determine the minimum necessary effectiveness and compliance of masks or respirators to mitigate a pandemic. We compared societal costs and benefits of providing surgical masks or N-95 respirators to 80% of the population. We measured outcomes in costs, infections and deaths averted, quality-adjusted life-years (QALYs), and incremental cost-effectiveness. We estimated transmissibility, morbidity and mortality of Influenza A from the literature. We estimated costs from the literature and expert opinions of public health and hospital officials. We tested all parameter assumptions in sensitivity analyses.

Result: At R₀ (the number of secondary infections caused by each primary infection) of 1.6, use of masks or respirators with a 52% efficacy x compliance parameter (product of how effective the mask or respirator is and percent of contacts during which individuals wear it) can end the pandemic (effective R₀ ≤ 1). This strategy gains 433,000 QALYs for $1.48 trillion at a cost of $9,400 per QALY as compared to no intervention.

Conclusion: The effectiveness of surgical masks and N-95 respirators in mitigating an influenza pandemic depends on their efficacy, compliance, and reproductive rate of the pandemic virus. Researchers should determine mask and respirator efficacy so public health officials and policymakers can target necessary compliance levels to mitigate a pandemic.