Angelique E Boutzoukas1,2, Kanecia O Zimmerman1,2,3, Moira Inkelas4,5, M Alan Brookhart6, Daniel K Benjamin1,2,3, Sabrina Butteris8, Shawn Koval9, Gregory P DeMuri8, Vladimir G Manuel5,10, Michael J Smith2, Kathleen A McGann2, Ibukunoluwa C Kalu2, David J Weber11, Amy Falk12, Andi L Shane13,14, Jennifer E Schuster15, Jennifer L Goldman15, Jesse Hickerson1, Vroselyn Benjamin1, Laura Edwards1, Tyler R Erickson1, Daniel K Benjamin1,2,3. 1. Duke Clinical Research Institute. 2. Departments of Pediatrics. 3. Co-Chair, The ABC Science Collaborative, Durham, North Carolina. 4. Fielding School of Public Health. 5. Clinical and Translational Science Institute, University of California Los Angeles, Los Angeles, California. 6. Population Health Sciences, Duke University School of Medicine, Durham, North Carolina. 7. Clemson University, Clemson, South Carolina. 8. Department of Pediatrics, University of Wisconsin School of Medicine & Public Health, Maddison, Wisconsin. 9. University of Wisconsin Health, Healthy Kids Collaborative, Madison, Wisconsin. 10. University of California David Geffen School of Medicine, Los Angeles, California. 11. Division of Infectious Diseases, School of Medicine, University of North Carolina, Chapel Hill, North Carolina. 12. Department of Pediatrics, Aspirus Doctors Clinic, Wisconsin Rapids, Wisconsin. 13. Emory University School of Medicine, Atlanta, Georgia. 14. Department of Pediatrics, Children's Healthcare of Atlanta, Atlanta, Georgia. 15. Division of Pediatric Infectious Diseases, Children's Mercy Kansas City, Kansas City, Missouri.
Abstract
OBJECTIVES: Throughout the COVID-19 pandemic, masking has been a widely used mitigation practice in kindergarten through 12th grade (K-12) school districts to limit within-school transmission. Prior studies attempting to quantify the impact of masking have assessed total cases within schools; however, the metric that more optimally defines effectiveness of mitigation practices is within-school transmission, or secondary cases. We estimated the impact of various masking practices on secondary transmission in a cohort of K-12 schools. METHODS: We performed a multistate, prospective, observational, open cohort study from July 26, 2021 to December 13, 2021. Districts reported mitigation practices and weekly infection data. Districts that were able to perform contact tracing and adjudicate primary and secondary infections were eligible for inclusion. To estimate the impact of masking on secondary transmission, we used a quasi-Poisson regression model. RESULTS: A total of 1 112 899 students and 157 069 staff attended 61 K-12 districts across 9 states that met inclusion criteria. The districts reported 40 601 primary and 3085 secondary infections. Six districts had optional masking policies, 9 had partial masking policies, and 46 had universal masking. In unadjusted analysis, districts that optionally masked throughout the study period had 3.6 times the rate of secondary transmission as universally masked districts; and for every 100 community-acquired cases, universally masked districts had 7.3 predicted secondary infections, whereas optionally masked districts had 26.4. CONCLUSIONS: Secondary transmission across the cohort was modest (<10% of total infections) and universal masking was associated with reduced secondary transmission compared with optional masking.
OBJECTIVES: Throughout the COVID-19 pandemic, masking has been a widely used mitigation practice in kindergarten through 12th grade (K-12) school districts to limit within-school transmission. Prior studies attempting to quantify the impact of masking have assessed total cases within schools; however, the metric that more optimally defines effectiveness of mitigation practices is within-school transmission, or secondary cases. We estimated the impact of various masking practices on secondary transmission in a cohort of K-12 schools. METHODS: We performed a multistate, prospective, observational, open cohort study from July 26, 2021 to December 13, 2021. Districts reported mitigation practices and weekly infection data. Districts that were able to perform contact tracing and adjudicate primary and secondary infections were eligible for inclusion. To estimate the impact of masking on secondary transmission, we used a quasi-Poisson regression model. RESULTS: A total of 1 112 899 students and 157 069 staff attended 61 K-12 districts across 9 states that met inclusion criteria. The districts reported 40 601 primary and 3085 secondary infections. Six districts had optional masking policies, 9 had partial masking policies, and 46 had universal masking. In unadjusted analysis, districts that optionally masked throughout the study period had 3.6 times the rate of secondary transmission as universally masked districts; and for every 100 community-acquired cases, universally masked districts had 7.3 predicted secondary infections, whereas optionally masked districts had 26.4. CONCLUSIONS: Secondary transmission across the cohort was modest (<10% of total infections) and universal masking was associated with reduced secondary transmission compared with optional masking.
Authors: Gianni Parisi; Véronique Renault; Marie-France Humblet; Nicolas Ochelen; Anh Nguyet Diep; Michèle Guillaume; Anne-Françoise Donneau; Fabrice Bureau; Laurent Gillet; Anne-Catherine Lange; Fabienne Michel; Sébastien Fontaine; Claude Saegerman Journal: Int J Environ Res Public Health Date: 2022-09-13 Impact factor: 4.614