Background: The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread wildly across the world. In March of 2020, almost all kindergarten through 12th grade (K-12) schools were closed in the United States in an urgent attempt to curb the pandemic in the absence of effective therapeutics or vaccination. Thirteen months since then, schools remain partially closed. Accumulated evidence suggests that children and adolescents are not the primary facilitators of transmission, limiting the restrictive effects of school closures on disease transmission. The negative effects of school closures on K-12 students need to be systematically reviewed.Methods: Following the guideline of Preferred Reporting Items for Systematic Reviews and Meta-analyzes, a comprehensive literature search from PubMed, EMBASE, Cochrane Library, Scopus, and Web of Science regarding school closures and its impact on K-12 students was conducted. The primary outcomes included the impact of school closures on the mitigation of the pandemic and the resulting public health concerns of K-12 students.Results: Prolonged school closures possessed negative effects on K-12 students' physical, mental, and social well-being and reduced the number of health and social workers, hindering the reopening of the country.Conclusions: School closures were over-weighted against the mitigation of coronavirus disease 2019 (COVID-19) transmission. A safe reopening of all K-12 schools in the United States should be of top priority.Abbreviations: COVID-19 = coronavirus disease 2019, K-12 = kindergarten through 12th grade, SARS-CoV-2 = severe acute respiratory syndrome coronavirus 2.

Sociodemographic factors have been found to be associated with the transmission of coronavirus disease 2019 , yet most studies focused on the period before the proliferation of vaccination and obtained inconclusive results. In this crosssectional study, the infections, deaths, incidence rates, case fatalities, and mortalities of Virginia's 133 jurisdictions during the prevaccination and post-vaccination periods were compared, and their associations with demographic and socioeconomic factors were studied. The cumulative infections and deaths and medians of incidence rates, case fatalities, and mortalities of COVID-19 in 133 Virginia jurisdictions were significantly higher during the post-vaccination period than during the pre-vaccination period. A variety of demographic and socioeconomic risk factors were significantly associated with COVID-19 prevalence in Virginia. Multiple linear regression analysis suggested that demographic and socioeconomic factors contributed up to 80% of the variation in the infections, deaths, and incidence rates and up to 53% of the variation in the case fatalities and mortalities of COVID-19 in Virginia. The demographic and socioeconomic determinants differed during the pre-and post-vaccination periods. The developed multiple linear regression models could be used to effectively characterize the impact of demographic and socioeconomic factors on the infections, deaths, and incidence rates of COVID-19 in Virginia.