To wear, or not to wear, that is the question: Observing mask usage at a university during the COVID-19 pandemic

RATIONALE: Correct mask usage is an important mitigation measure against SARS-CoV-2 infection. Despite requiring mask usage and other mitigation measures for students, staff, and faculty, a large university experienced a rapid increase in coronavirus disease 2019 (COVID-19) cases within the two weeks of opening in August 2020. This study aimed to assess the prevalence of mask usage at the university. METHODS: For seven weeks during October 5-November 22, eight trained observers conducted weekly observations of mask usage at two sites per week. A total of 18 on-campus and 4 near-campus locations served as observation sites, including student centers, libraries, classroom buildings, dormitories, student dining, transportation sites, nearcampus apartment buildings, a grocery store, and a football stadium. An observation period lasted until 40 observations per site were made or one hour elapsed, whichever occurred first. Observations occurred at different times on multiple days of the week from a fixed location at each site. Observers monitored mask usage of either every 3rd or every 10th person depending upon person-density, selecting only one sampling strategy per observation period. For each observed person, observers recorded whether a mask was worn, and for those wearing masks, if the mask was worn correctly (i.e., mouth and nose covered) and type of mask worn (i.e., cloth, surgical, N-95-type, gaiter, other). Percentage of persons wearing masks and percentage wearing masks correctly was calculated and communicated weekly to the university. RESULTS: The study included a total of 3,144 observations (mean = 449 per week [range: 389-510]). The mean weekly percentage of persons wearing masks was 83.9% (range = 79.6%-88.3%). Among the 2,637 people observed wearing masks, the mean weekly percentage wearing them correctly was 86.0% (range = 84.0% to 90.4%). The mean weekly percentage wearing masks varied by site type and ranged from 78.7% at transportation sites to 91.0% at library sites. Mask types observed were cloth (62.4%), surgical (30.5%), neck gaiter (5.8%), and N-95-type (1.1%). CONCLUSION: Approximately 7 in 10 persons observed were wearing a mask and wearing it correctly. Observed persons most often wore cloth masks and observed mask usage varied by site type. Conducting observational studies using standardized methodology can provide rapid information about mask wearing in a population. Such information can inform additional efforts at a university that experienced a COVID-19 outbreak to help improve compliance with correct mask wearing, one effective mitigation strategy against SARS-CoV-2 transmission.