Correction: Inferring school district learning modalities during the COVID-19 pandemic with a hidden Markov model.

[This corrects the article DOI: 10.1371/journal.pone.0292354.].

Inferring school district learning modalities during the COVID-19 pandemic with a hidden Markov model.

During the COVID-19 pandemic, many public schools across the United States shifted from fully in-person learning to alternative learning modalities such as hybrid and fully remote learning. In this study, data from 14,688 unique school districts from August 2020 to June 2021 were collected to track changes in the proportion of schools offering fully in-person, hybrid and fully remote learning over time. These data were provided by Burbio, MCH Strategic Data, the American Enterprise Institute's Return to Learn Tracker and individual state dashboards. Because the modalities reported by these sources were incomplete and occasionally misaligned, a model was needed to combine and deconflict these data to provide a more comprehensive description of modalities nationwide. A hidden Markov model (HMM) was used to infer the most likely learning modality for each district on a weekly basis. This method yielded higher spatiotemporal coverage than any individual data source and higher agreement with three of the four data sources than any other single source. The model output revealed that the percentage of districts offering fully in-person learning rose from 40.3% in September 2020 to 54.7% in June of 2021 with increases across 45 states and in both urban and rural districts. This type of probabilistic model can serve as a tool for fusion of incomplete and contradictory data sources in order to obtain more reliable data in support of public health surveillance and research efforts.

Dispensing of Oral Antiviral Drugs for Treatment of COVID-19 by Zip Code-Level Social Vulnerability - United States, December 23, 2021-May 21, 2022.

The COVID-19 pandemic has highlighted and exacerbated long-standing inequities in the social determinants of health (1-3). Ensuring equitable access to effective COVID-19 therapies is essential to reducing health disparities. Molnupiravir (Lagevrio) and nirmatrelvir/ritonavir (Paxlovid) are oral antiviral agents effective at preventing hospitalization and death in patients with mild to moderate COVID-19 who are at high risk* for progression to severe COVID-19 when initiated within 5 days of symptom onset. These medications received Emergency Use Authorization from the Food and Drug Administration (FDA) in December 2021† and were made available at no cost to recipients through the U.S. Department of Health and Human Services (HHS) on December 23, 2021. Beginning March 7, 2022, a series of strategies was implemented to expand COVID-19 oral antiviral access, including the launch of the Test to Treat initiative.§ Data from December 23, 2021-May 21, 2022, were analyzed to describe oral antiviral prescription dispensing overall and by week, stratified by zip code social vulnerability. Zip codes represented areas classified as low, medium, or high social vulnerability; approximately 20% of U.S. residents live in low-, 31% in medium-, and 49% in high-social vulnerability zip codes.¶ During December 23, 2021-May 21, 2022, a total of 1,076,762 oral antiviral prescriptions were dispensed (Lagevrio = 248,838; Paxlovid = 827,924). Most (70.3%) oral antivirals were dispensed during March 7-May 21, 2022. During March 6, 2022-May 21, 2022, the number of oral antivirals dispensed per 100,000 population increased from 3.3 to 77.4 in low-, from 4.5 to 70.0 in medium-, and from 7.8 to 35.7 in high-vulnerability zip codes. The number of oral antivirals dispensed rose substantially during the overall study period, coincident with the onset of initiatives to increase access. However, by the end of the study period, dispensing rates in high-vulnerability zip codes were approximately one half the rates in medium- and low-vulnerability zip codes. Additional public health, regulatory, and policy efforts might help decrease barriers to oral antiviral access, particularly in communities with high social vulnerability.

COVID-19-Related School Closures and Learning Modality Changes - United States, August 1-September 17, 2021.

Beginning in January 2021, the U.S. government prioritized ensuring continuity of learning for all students during the COVID-19 pandemic (1). To estimate the extent of COVID-19-associated school disruptions, CDC and the Johns Hopkins University Applied Physics Laboratory used a Hidden Markov Model (HMM) (2) statistical approach to estimate the most likely actual learning modality based on patterns observed in past data, accounting for conflicting or missing information and systematic Internet searches (3) for COVID-19-related school closures. This information was used to assess how many U.S. schools were open, and in which learning modalities, during August 1-September 17, 2021. Learning modalities included 1) full in-person learning, 2) a hybrid of in-person and remote learning, and 3) full remote learning.

Pediatric COVID-19 Cases in Counties With and Without School Mask Requirements - United States, July 1-September 4, 2021.

Consistent and correct mask use is a critical strategy for preventing the transmission of SARS-CoV-2, the virus that causes COVID-19 (1). CDC recommends that schools require universal indoor mask use for students, staff members, and others in kindergarten through grade 12 (K-12) school settings (2). As U.S. schools opened for the 2021-22 school year in the midst of increasing community spread of COVID-19, some states, counties, and school districts implemented mask requirements in schools. To assess the impact of masking in schools on COVID-19 incidence among K-12 students across the United States, CDC assessed differences between county-level pediatric COVID-19 case rates in schools with and without school mask requirements.