The Centers for Disease Control allows rapid antigen testing (RAT) towards the end of a 5-day isolation for COVID-19 infection to determine eligibility to leave isolation. The impact of a test-to-return (TTR) program in schools is unknown. In January 2022 a Massachusetts school district initiated a TTR program utilizing a single school-administered RAT on days 5-9 after symptom onset or positive test, whichever was first. Of 636 students with COVID-19 infection, 408 (64.2%) participated in TTR; of these, 128 (31.4%) had a positive TTR rapid antigen test. Students who were symptomatic at any time during their infection were more likely to have a positive TTR than those who were never symptomatic (43.1% vs. 17.3%); positivity rates were lower when TTR was performed later during days 6-9. TTR may identify students who carry higher viral loads after recovery from COVID-19 infection thereby extending their isolation, while facilitating earlier return of those with negative results.
The nematode C. elegans uses rhythmic muscle contractions (pumps) of the pharynx, a tubular feeding organ, to filter, transport, and crush food particles. A number of feeding mutants have been identified, including those with slow pharyngeal pumping rate, weak muscle contraction, defective muscle relaxation, and defective grinding of bacteria. Many aspects of these pharyngeal behavioral defects and how they affect pharyngeal function are not well understood. For example, the behavioral deficits underlying inefficient particle transport in 'slippery' mutants have been unclear. Here we use high speed video microscopy to describe pharyngeal pumping behaviors and particle transport in wild-type animals and in feeding mutants. Different 'slippery' mutants exhibit distinct defects including weak isthmus contraction, failure to trap particles in the anterior isthmus, and abnormal timing of contraction and relaxation in pharyngeal compartments. Our results show that multiple deficits in pharyngeal timing or contraction can cause defects in particle transport.
ImportanceSchool-associated SARS-CoV-2 transmission is described as uncommon, although the true transmission rate is unknown.ObjectiveTo identify the SARS-CoV-2 secondary attack rate (SAR) in schools and factors associated with transmission.Design, Setting, and ParticipantsThis cohort study examined the risk of school-based transmission of SARS-CoV-2 among kindergarten through grade 12 students and staff in 10 Massachusetts school districts during 2 periods: fall 2020/spring 2021 (F20/S21) and fall 2021 (F21). School staff collected data on SARS-CoV-2 index cases and school-based contacts, and SAR was defined as the proportion of contacts acquiring SARS-CoV-2 infection.ExposureSARS-CoV-2.Main Outcomes and MeasuresPotential factors associated with transmission, including grade level, masking, exposure location, vaccination history, and Social Vulnerability Index (SVI), were analyzed using univariable and multivariable logistic regression models.ResultsFor F20/S21, 8 school districts (70 schools, >33 000 students) were included and reported 435 index cases (151 staff, 216 students, and 68 missing role) with 1771 school-based contacts (278 staff, 1492 students, and 1 missing role). For F21, 5 districts (34 schools, >18 000 students) participated and reported 309 index cases (37 staff, 207 students, and 65 missing role) with 1673 school-based contacts (107 staff and 1566 students). The F20/S21 SAR was 2.2% (lower bound, 1.6%; upper bound, 26.7%), and the F21 SAR was 2.8% (lower bound, 2.6%; upper bound, 7.4%). In multivariable analysis, during F20/S21, masking was associated with a lower odds of transmission compared with not masking (odds radio [OR], 0.12; 95% CI, 0.04-0.40; P < .001). In F21, classroom exposure vs out-of-classroom exposure was associated with increased odds of transmission (OR, 2.47; 95% CI, 1.07-5.66; P = .02); a fully vaccinated vs unvaccinated contact was associated with a lower odds of transmission (OR, 0.04; 95% CI, 0.00-0.62; P < .001). In both periods, a higher SVI was associated with a greater odds of transmission.Conclusions and RelevanceIn this study of Massachusetts schools, the SAR for SARS-CoV-2 among school-based contacts was low during 2 periods, and factors associated with transmission risk varied over time. These findings suggest that ongoing surveillance efforts may be essential to ensure that both targeted resources and mitigation practices remain optimal and relevant for disease prevention.
BACKGROUNDPer Centers for Disease Control and Prevention guidance, students with COVID‐19 may end isolation after 5 days if symptoms are improving; some individuals may still be contagious. Rapid antigen testing identifies possibly infectious virus. We report on a test‐to‐return (TTR) program in a Massachusetts school district to inform policy decisions about return to school after COVID‐19.METHODSDuring the 2021‐2022 Omicron BA.1 surge, students with COVID‐19 could return on day 6‐10 if they met symptom criteria and had a negative rapid test; students with positive rapid tests and those who declined TTR remained isolated until day 11. TTR positivity rates were compared by grade level, vaccination status, symptom status, and day of infection.RESULTS31.4% of students had a positive TTR rapid test; there were no differences by grade or vaccination status. Ever‐symptomatic students were more likely to have a positive rapid test (75/174 [43.1%] vs 18/104 [17.3%]). For ever‐symptomatic students, TTR positivity decreased by day of infection.CONCLUSIONSA substantial proportion of students may still be contagious 6 days after onset of COVID‐19 infection. TTR programs may increase or reduce missed school days, depending on when return is otherwise allowed (day 6 or 11). The impact of TTR programs on school‐associated transmission remains unknown.
The nematode C. elegans uses rhythmic muscle contractions and relaxations called pumps to filter, transport, and crush food particles. A number of feeding mutants have been identified, including those with slow pharyngeal pumping rate, weak muscle contraction, defective muscle relaxation, and defective grinding of bacteria. Many aspects of these pharyngeal behavioral defects and how they affect pharyngeal function are not well understood. For example, the behavioral deficits underlying inefficient particle transport in ‘slippery’ mutants have been unclear. Here we use high speed video microscopy to describe pharyngeal pumping behaviors and particle transport in wild-type animals and in feeding mutants. Different ‘slippery’ mutants exhibit distinct defects including weak isthmus contraction, failure to trap particles in the anterior isthmus, and abnormal timing of contraction and relaxation in pharyngeal compartments. Our results show that multiple deficits in pharyngeal timing or contraction can cause defects in particle transport.
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