According to a St. Louis University study, in the months after summer mask mandates were imposed in some St. Louis County municipalities, the daily growth rate in reported COVID-19 cases was 40 percent below those reported by nearby areas that did not adopt similar protective measures.

The report, released this week by St. Louis University’s College for Public Health and Social Justice, concludes mask mandates in St. Louis and St. Louis County “quickly and drastically slowed coronavirus infection rates” compared with outlying counties.