Test-to-Stay in Kindergarten Through 12th Grade Schools After Household Exposure to Severe Acute Respiratory Syndrome Coronavirus 2.

BACKGROUND: Test-to-stay (TTS) is a strategy to limit school exclusion following an exposure to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We evaluated the use of TTS within universally masked kindergarten through 12th grade (K-12) school settings following household SARS-CoV-2 exposure. METHODS: Three hundred twenty-two participants were enrolled. Serial rapid antigen testing was performed up to 15 days post-exposure. Analysis-eligible participants completed the 15-day testing protocol, tested positive any time during the testing window, or received a negative test on or after day 9. Primary outcomes included within-school tertiary attack rate (TAR) (test positivity among close contacts of positive TTS participants), and school days saved among TTS participants. RESULTS: Seventy-three of 265 analysis-eligible participants tested positive for SARS-CoV-2 (secondary attack rate of 28% [95% CI: 16-63%]). Among 77 within-school close contacts, 2 were positive (TAR = 3% [95% CI: 1-5%]). Participant absences were limited to 338 days, resulting in 82% of 1849 school days saved. IMPLICATIONS FOR SCHOOL HEALTH POLICY, PRACTICE, AND EQUITY: TTS facilitates continued in-person learning and can greatly reduce the number of missed school days. CONCLUSIONS: Within universally masked K-12 schools, TTS is a safe alternative to school exclusion following household SARS-CoV-2 exposure.

Test-to-Stay After SARS-CoV-2 Exposure: A Mitigation Strategy for Optionally Masked K-12 Schools.

OBJECTIVES: We evaluated the impact of a test-to-stay (TTS) program on within-school transmission and missed school days in optionally masked kindergarten through 12th grade schools during a period of high community severe acute respiratory syndrome coronavirus 2 transmission. METHODS: Close contacts of those with confirmed severe acute respiratory syndrome coronavirus 2 infection were eligible for enrollment in the TTS program if exposure to a nonhousehold contact occurred between November 11, 2021 and January 28, 2022. Consented participants avoided school exclusion if they remained asymptomatic and rapid antigen testing at prespecified intervals remained negative. Primary outcomes included within-school tertiary attack rate (test positivity among close contacts of positive TTS participants) and school days saved among TTS participants. We estimated the number of additional school-acquired cases resulting from TTS and eliminating school exclusion. RESULTS: A total of 1675 participants tested positive or received at least 1 negative test between days 5 and 7 and completed follow-up; 92% were students and 91% were exposed to an unmasked primary case. We identified 201 positive cases. We observed a tertiary attack rate of 10% (95% confidence interval: 6%-19%), and 7272 (89%) of potentially missed days were saved through TTS implementation. We estimated 1 additional school-acquired case for every 21 TTS participants remaining in school buildings during the entire study period. CONCLUSIONS: Even in the setting of high community transmission, a TTS strategy resulted in substantial reduction in missed school days in optionally masked schools.

Test-to-Stay After Exposure to SARS-CoV-2 in K-12 Schools.

OBJECTIVES: We evaluated the safety and efficacy of a test-to-stay program for unvaccinated students and staff who experienced an unmasked, in-school exposure to someone with confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Serial testing instead of quarantine was offered to asymptomatic contacts. We measured secondary and tertiary transmission rates within participating schools and in-school days preserved for participants. METHODS: Participating staff or students from universally masked districts in North Carolina underwent rapid antigen testing at set intervals up to 7 days after known exposure. Collected data included location or setting of exposure, participant symptoms, and school absences up to 14 days after enrollment. Outcomes included tertiary transmission, secondary transmission, and school days saved among test-to-stay participants. A prespecified interim safety analysis occurred after 1 month of enrollment. RESULTS: We enrolled 367 participants and completed 14-day follow-up on all participants for this analysis. Nearly all (215 of 238, 90%) exposure encounters involved an unmasked index case and an unmasked close contact, with most (353 of 366, 96%) occurring indoors, during lunch (137 of 357, 39%) or athletics (45 of 357, 13%). Secondary attack rate was 1.7% (95% confidence interval: 0.6%-4.7%) based on 883 SARS-CoV-2 serial rapid antigen tests with results from 357 participants; no tertiary cases were identified, and 1628 (92%) school days were saved through test-to-stay program implementation out of 1764 days potentially missed. CONCLUSION: After unmasked in-school exposure to SARS-CoV-2, even in a mostly unvaccinated population, a test-to-stay strategy is a safe alternative to quarantine.

A School-Based SARS-CoV-2 Testing Program: Testing Uptake and Quarantine Length After In-School Exposures.

OBJECTIVES: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-related quarantines, which are required after close contact with infected individuals, have substantially disrupted in-person education for kindergarten through 12th grade (K-12) students. In recent recommendations, shortened durations of quarantine are allowed if a negative SARS-CoV-2 test result is obtained at 5 to 7 days postexposure, but access to testing remains limited. We hypothesized that providing access to in-school SARS-CoV-2 testing postexposure would increase testing and reduce missed school days. METHODS: This prospective cohort study was conducted in one large public K-12 school district in North Carolina and included 2 periods: preimplementation (March 15, 2021, to April 21, 2021) and postimplementation (April 22, 2021, to June 4, 2021), defined around initiation of an in-school SARS-CoV-2 testing program in which on-site access to testing is provided. Number of quarantined students and staff, testing uptake, test results, and number of missed school days were analyzed and compared between the preimplementation and postimplementation periods. RESULTS: Twenty-four schools, including 12 251 in-person learners, participated in the study. During preimplementation, 446 close contacts were quarantined for school-related exposures; 708 close contacts were quarantined postimplementation. Testing uptake after school-related exposures increased from 6% to 40% (95% confidence interval: 23% to 45%) after implementation, and 89% of tests were conducted in-school. After in-school testing implementation, close contacts missed ∼1.5 fewer days of school (95% confidence interval: -2 to -1). CONCLUSIONS: Providing access to in-school testing may be a worthwhile mechanism to increase testing uptake after in-school exposures and minimize missed days of in-person learning, thereby mitigating the pandemic's ongoing impact on children.

Three new silver uranyl diphosphonates: structures and properties.

The hydrothermal reaction of uranium trioxide and methylenediphosphonic acid in the presence of silver nitrate resulted in the formation of three new uranyl coordination polymers: AgUO2[CH2(PO3)(PO3H)] (Ag-1), [Ag2(H2O)1.5]{(UO2)2[CH2(PO3)2]F2}·(H2O)0.5 (Ag-2), and Ag2UO2[CH2(PO3)2] (Ag-3). All consist of uranyl pentagonal bipyramids that form two-dimensional layered structures. Ag-1 and Ag-3 possess the same structural building unit, but the structures are different; Ag-3 is formed through edge-sharing of F atoms to form UO5F2 dimers. The pH and silver cation have significant effects on the structure that is synthesized. Raman spectra of single crystals of Ag-1, Ag-2, and Ag-3 reveal v1 UO2(2+) symmetric stretches of 816 and 829, 822, and 802 cm(-1), respectively. Electronic structure calculations were performed using the projector augmented wave (PAW) method with density functional theory (DFT) to gain insight into the nature of bonding and electronic characteristics of the synthesized compounds. Herein, we report the syntheses, crystal structures, Raman spectroscopy, and luminescent behavior of these three compounds.

Electronic structure and energetics of tetragonal SrCuO2 and its high-pressure superstructure phase.

First-principles calculations have been used to investigate the electronic structure and energetics of the simple tetragonal SrCuO2 (P4=mmm) and its high-pressure tetragonal superstructure (P4=mmm). Based on the calculations, the high-pressure phase is metastable as compared with the low pressure tetragonal phase, with an energy difference of 0.13 eV per SrCuO2 formula unit. The energy barrier to the transition from the superstructure to the simple tetragonal structure is 0.24 eV at 7 GPa; thus, high temperatures are required to synthesize the latter. Among the possible structural configurations resulting from the partially occupied oxygen site in the superstructure phase, the most stable structure has a space group PN4m2, reduced from that of the simple tetragonal structure P4=mmm. The detailed analysis of the electronic band structures of the simple tetragonal and superstructure phases suggests that the out-of-plane buckling of the O atoms in the superstructure leads to significant decrease in the O p-Cu d orbital overlap, allowing the energy of the system to be lowered, which is necessary for the structural stability. An understanding of the electronic structure and energetics of the high-pressure superstructure phase and its relation to the simple tetragonal phase provides a basis for exploring the physical properties of the infinite layer, high-TC superconductor.