PolicyLab

In a new Health Affairs study analyzing the effectiveness of county-level mask mandates at reducing the spread of COVID-19 during a period of high community transmission in 2020, PolicyLab researcher Dr. Jing Huang and a team of researchers from PolicyLab and the University of Pennsylvania’s Perelman School of Medicine, found that mandates reduced case incidence, but that effect waned over time.

The study, which is the largest to assess the impact of masking mandates in the U.S., included nearly 400 diverse counties and focused on larger counties experiencing moderate to substantial community transmission in the spring and summer of 2020. The team found that after six weeks of enforced mask mandates, COVID-19 transmission declined by 33% overall. The strongest effects were seen in large, urban counties, where COVID-19 transmission was 48% at six weeks among those that initiative versus did not initiate mask mandates. But, the impact of mask mandates lessened between six and eight weeks.

Overall, this study supports the use of mask mandates, particularly in large, urban counties, for lessening the worst surges of the pandemic. However, the exact factors contributing to the benefit of mask mandates, such as enforcement, are still unknown and need to be further explored. 

Be sure to read the Health Affairs study here and an accompanying blog post outlining the findings here.