Objectives: To evaluate the effectiveness of face mask mandates in four suburban communities in the metropolitan Boston area during the SARS-CoV2 Omicron surge.

Background: Face mask mandates have been implemented by local, state and national governments to limit the transmission of illness during the SARS-CoV2 pandemic.

Methods: A retrospective review of state reported, PCR positive cases of SARS-CoV2 and vaccination rates in four communities during the Omicron surge from 01/11/21-01/31/22. Data was analyzed using descriptive statistics.

Results: Two communities had a face mask mandate in place for all indoor public spaces throughout the study period, and two communities did not. Brookline (population 59,180, fully vaccinated rate per capita 62%) and Newton (population 88,593, vaccination rate 87%) implemented face mask mandates prior to the surge on 08/27/21 and 09/02/21, respectively, that remained in place through 02/18/22. Needham (population 31,248, vaccination rate 93%) and Framingham (population 72,308, vaccination rate 76%) issued mask recommendations but not a mask mandate. SARS-CoV2 percent positive rate per 100,000 population, reported weekly for each community is shown in Figure 1. Prior to Omicron, on 10/14/21 percent positive rates were 1% or less in all four communities. Percent positivity at the peak of Omicron was lower in Newton (13.18%) and Brookline (12.28%) than in Needham (14.92%) and Framingham (22.38%). Brookline had the lowest peak positivity rate and the lowest vaccination rate. Percent positivity also peaked and declined earlier in both communities with mask mandates.

Conclusion: In this study, suburban communities with mask mandates had a lower SARS-CoV2 peak percent positivity rate and an earlier peak than communities without mask mandates. Face mask requirements in indoor public spaces may reduce transmission of SARS-CoV2 during variant surges, and may be particularly effective in communities with lower vaccination rates.