Evaluation of Test to Stay Strategy on Secondary and Tertiary Transmission of SARS-CoV-2 in K-12 Schools - Lake County, Illinois, August 9-October 29, 2021

SARS-CoV-2 Test-to-Stay in Daycare

BACKGROUND AND OBJECTIVES

Test-to-stay concepts apply serial testing of children in daycare after exposure to SARS-CoV-2 without use of quarantine. This study aims to assess the safety of a test-to-stay screening in daycare facilities.

METHODS

714 daycare facilities and approximately 50 000 children ≤6 years in Cologne, Germany participated in a SARS-CoV-2 Pool-polymerase chain reaction (PCR) screening from March 2021 to April 2022. The screening initially comprised post-exposure quarantine and was adapted to a test-to-stay approach during its course. To assess safety of the test-to-stay approach, we explored potential changes in frequencies of infections among children after the adaptation to the test-to-stay approach by applying regression discontinuity in time (RDiT) analyses. To this end, PCR-test data were linked with routinely collected data on reported infections in children and analyzed using ordinary least squares regressions.

RESULTS

219 885 Pool-PCRs and 352 305 Single-PCRs were performed. 6440 (2.93%) Pool-PCRs tested positive, and 17 208 infections in children were reported. We estimated that during a period of 30 weeks, the test-to-stay concept avoided between 7 and 20 days of quarantine per eligible daycare child. RDiT revealed a 26% reduction (Exp. Coef: 0.74, confidence interval 0.52-1.06) in infection frequency among children and indicated no significant increase attributable to the test-to-stay approach. This result was not sensitive to adjustments for 7-day incidence, season, SARS-CoV-2 variant, and socioeconomic status.

CONCLUSIONS

Our analyses provide evidence that suggest safety of the test-to-stay approach compared with quarantine measures. This approach offers a promising option to avoid use of quarantine after exposure to respiratory pathogens in daycare settings.

Workplace interventions to reduce the risk of SARS-CoV-2 infection outside of healthcare settings

BACKGROUND

Although many people infected with SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) experience no or mild symptoms, some individuals can develop severe illness and may die, particularly older people and those with underlying medical problems. Providing evidence-based interventions to prevent SARS-CoV-2 infection has become more urgent with the potential psychological toll imposed by the coronavirus disease 2019 (COVID-19) pandemic. Controlling exposures to occupational hazards is the fundamental method of protecting workers. When it comes to the transmission of viruses, workplaces should first consider control measures that can potentially have the most significant impact. According to the hierarchy of controls, one should first consider elimination (and substitution), then engineering controls, administrative controls, and lastly, personal protective equipment. This is the first update of a Cochrane review published 6 May 2022, with one new study added.

OBJECTIVES

To assess the benefits and harms of interventions in non-healthcare-related workplaces aimed at reducing the risk of SARS-CoV-2 infection compared to other interventions or no intervention.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, Web of Science Core Collections, Cochrane COVID-19 Study Register, World Health Organization (WHO) COVID-19 Global literature on coronavirus disease, ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform, and medRxiv to 13 April 2023.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and non-randomised studies of interventions. We included adult workers, both those who come into close contact with clients or customers (e.g. public-facing employees, such as cashiers or taxi drivers), and those who do not, but who could be infected by coworkers. We excluded studies involving healthcare workers. We included any intervention to prevent or reduce workers' exposure to SARS-CoV-2 in the workplace, defining categories of intervention according to the hierarchy of hazard controls (i.e. elimination; engineering controls; administrative controls; personal protective equipment).

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Our primary outcomes were incidence rate of SARS-CoV-2 infection (or other respiratory viruses), SARS-CoV-2-related mortality, adverse events, and absenteeism from work. Our secondary outcomes were all-cause mortality, quality of life, hospitalisation, and uptake, acceptability, or adherence to strategies. We used the Cochrane RoB 2 tool to assess risk of bias, and GRADE methods to evaluate the certainty of evidence for each outcome.

MAIN RESULTS

We identified 2 studies including a total of 16,014 participants. Elimination-of-exposure interventions We included one study examining an intervention that focused on elimination of hazards, which was an open-label, cluster-randomised, non-inferiority trial, conducted in England in 2021. The study compared standard 10-day self-isolation after contact with an infected person to a new strategy of daily rapid antigen testing and staying at work if the test is negative (test-based attendance). The trialists hypothesised that this would lead to a similar rate of infections, but lower COVID-related absence. Staff (N = 11,798) working at 76 schools were assigned to standard isolation, and staff (N = 12,229) working at 86 schools were assigned to the test-based attendance strategy. The results between test-based attendance and standard 10-day self-isolation were inconclusive for the rate of symptomatic polymerase chain reaction (PCR)-positive SARS-CoV-2 infection (rate ratio (RR) 1.28, 95% confidence interval (CI) 0.74 to 2.21; 1 study; very low-certainty evidence). The results between test-based attendance and standard 10-day self-isolation were inconclusive for the rate of any PCR-positive SARS-CoV-2 infection (RR 1.35, 95% CI 0.82 to 2.21; 1 study; very low-certainty evidence). COVID-related absenteeism rates were 3704 absence days in 566,502 days-at-risk (6.5 per 1000 working days) in the control group and 2932 per 539,805 days-at-risk (5.4 per 1000 working days) in the intervention group (RR 0.83, 95% CI 0.55 to 1.25). We downgraded the certainty of the evidence to low due to imprecision. Uptake of the intervention was 71% in the intervention group, but not reported for the control intervention. The trial did not measure our other outcomes of SARS-CoV-2-related mortality, adverse events, all-cause mortality, quality of life, or hospitalisation. We found seven ongoing studies using elimination-of-hazard strategies, six RCTs and one non-randomised trial. Administrative control interventions We found one ongoing RCT that aims to evaluate the efficacy of the Bacillus Calmette-Guérin (BCG) vaccine in preventing COVID-19 infection and reducing disease severity. Combinations of eligible interventions We included one non-randomised study examining a combination of elimination of hazards, administrative controls, and personal protective equipment. The study was conducted in two large retail companies in Italy in 2020. The study compared a safety operating protocol, measurement of body temperature and oxygen saturation upon entry, and a SARS-CoV-2 test strategy with a minimum activity protocol. Both groups received protective equipment. All employees working at the companies during the study period were included: 1987 in the intervention company and 1798 in the control company. The study did not report an outcome of interest for this systematic review. Other intervention categories We did not find any studies in this category.

AUTHORS' CONCLUSIONS

We are uncertain whether a test-based attendance policy affects rates of PCR-positive SARS-CoV-2 infection (any infection; symptomatic infection) compared to standard 10-day self-isolation amongst school and college staff. A test-based attendance policy may result in little to no difference in absenteeism rates compared to standard 10-day self-isolation. The non-randomised study included in our updated search did not report any outcome of interest for this Cochrane review. As a large part of the population is exposed in the case of a pandemic, an apparently small relative effect that would not be worthwhile from the individual perspective may still affect many people, and thus become an important absolute effect from the enterprise or societal perspective. The included RCT did not report on any of our other primary outcomes (i.e. SARS-CoV-2-related mortality and adverse events). We identified no completed studies on any other interventions specified in this review; however, eight eligible studies are ongoing. More controlled studies are needed on testing and isolation strategies, and working from home, as these have important implications for work organisations.

What is the specific role of schools and daycares in COVID-19 transmission? A final report from a living rapid review

Due to rapidly evolving conditions, the question of how to safely operate schools and daycares remained a top priority throughout the COVID-19 pandemic. In response to growing and changing evidence, the National Collaborating Centre for Methods and Tools in Canada maintained a living rapid review on the role of schools and daycares in COVID-19 transmission to guide evidence-informed decision making. This Review presents the final iteration of this living rapid review. 31 sources were searched until Oct 17, 2022. In the final version, eligible studies reported data from Jan 1, 2021 onward on transmission of COVID-19 in school or daycare settings, the effect of infection prevention and control measures on transmission, or the effect of operating schools or daycares on community-level COVID-19 rates. As a rapid review, titles and abstracts were screened by a single reviewer with artificial intelligence integrated into later versions. Full-text screening, data extraction, and critical appraisal were completed by one reviewer and checked by a second reviewer. The Johanna Briggs Institute tools were used for critical appraisal. The certainty of evidence was assessed using the Grading of Recommendations Assessment, Development, and Evaluation approach, and results were synthesised narratively. Three citizen partners provided input for the final interpretation. This final update includes 73 primary studies. Secondary attack rates were low within school settings when infection prevention and control measures were in place (moderate certainty). Masks might reduce transmission, test-to-stay policies might not increase transmission risk compared with mandatory quarantine, cohorting and hybrid learning might make little to no difference in transmission (low certainty), and the effect of surveillance testing within schools remained inconclusive (very low certainty). Findings indicate that school settings do not substantially contribute to community incidence, hospitalisations, or mortality (low certainty). This living review provides a synthesis of global evidence for the role of schools and daycares during COVID-19, which might be helpful in future pandemics.

Secondary infections of COVID-19 in schools and the effectiveness of school-based interventions: a systematic review and meta-analysis

OBJECTIVES

This meta-analysis explored secondary infections of SARS-CoV-2 and the effectiveness of non-pharmaceutical interventions (NPIs) in school settings, with the aim of providing a reference to formulate scientific prevention and response strategies for similar major public health emergencies in specific settings.

STUDY DESIGN

This was a systematic review and meta-analysis.

METHODS

Systematic searches were conducted in PubMed, Web of Science and the Cochrane Library through to 1 August 2022 using the following key search terms: COVID-19, SARS-CoV-2, secondary attack rate, school, transmission, etc. The IVhet model was used for the meta-analysis, and the I2 index and Cochran's Q-test were used to assess heterogeneity. Publication bias was examined using Doi plot, Galbraith plots and Luis Furuya-Kanamori index. Prevalence Critical Appraisal Tool was used to assess the quality of the included articles, while Grading of Recommendations Assessment, Development, and Evaluation was used to rate the quality of the evidence. Subgroup analyses were conducted to explore the potential source of heterogeneity.

RESULTS

Thirty-four studies involving 226,727 school contacts and 2216 secondary cases were included in this study. The pooled secondary attack rates (SARs) of close contacts, staff contacts and student contacts were 0.67% (95% confidence interval [CI]: 0.11, 1.56), 0.79% (95% CI: 0.00, 6.72) and 0.50% (95% CI: 0.00, 4.48), respectively. Subgroup analysis suggested that multiple or specific combinations (e.g. the combination of contact restriction and hygiene action) of NPIs appeared to be associated with lower SARs.

CONCLUSIONS

The SAR of SARS-CoV-2 was low in schools. Multiple or specific combinations of prevention strategies appear to mitigate SARS-CoV-2 transmission in school settings. These findings provide a basis for continuous improvement of response strategies to major public health emergencies in the school environment.

Evaluating the Impact of Aevidum on Mental Health Knowledge, Attitudes, and Help-Seeking Behaviors in High School Students: A Mixed-Methods Study

PURPOSE

To compare Aevidum's school mental health curriculum vs the curriculum plus Aevidum clubs in a mixed-methods study including pre/post surveys, a randomized clinical trial, and qualitative interviews.

DESIGN

Concurrent mixed-methods: Aim 1) pre-post surveys evaluated curriculum only vs curriculum plus club schools separately regarding changes in knowledge, help-seeking, and school culture; Aim 2) randomized clinical trial compared curriculum only to curriculum plus club schools; Aim 3) qualitative school staff interviews enhanced understanding of school culture changes.

SETTING

Curriculum delivered to 9th graders at ten Pennsylvania high schools; 5 schools randomized to start clubs.

SUBJECTS

Students (surveys), staff (interviews).

INTERVENTION

Aevidum curriculum plus/minus club.

MEASURES

Aim 1, mixed effects linear and logistic regression models for longitudinal data were used to analyze survey items at each time point. Aim 2, the same regression models were used, except models included a fixed-effect for group and group by time interaction effect. Aim 3, interviews were transcribed; a codebook was developed followed by thematic analysis.

RESULTS

Pre-survey 2557 respondents; 49% female, 86% non-Hispanic white. Post-survey 737 (29% response rate). Aim 1, pre-post (Likert responses, larger numbers favorable) demonstrated increased student knowledge to identify depression (4.26 [4.19-4.33] to 4.59 [4.47-4.71], P < .001) and help a friend access support (4.30 [4.21-4.38] to 4.56 [4.40-4.71], P = .001). Help-seeking increased for phone helplines (1.61 [1.57-1.66] to 1.78 [1.70-1.86], P < .001), crisis textlines (1.60 [1.55-1.64] to 1.78 [1.70-1.86], P < .001), internet/websites (1.80 [1.75-1.85] to 1.99 [1.90-2.08], P < .001), school counselors (P = .005) and teachers (.013). Aim 2, no significant differences in knowledge, help-seeking or culture between curriculum only vs curriculum plus club schools. Aim 3, staff (n = 17) interviews supported reduced stigma and increased mental health referrals.

CONCLUSIONS

Aevidum's curriculum improved mental health knowledge and help-seeking; adding the club did not significantly change responses. Staff identified positive school culture impacts. Limitations include the lower post-survey response.

Keeping kids in school: modelling school-based testing and quarantine strategies during the COVID-19 pandemic in Australia

Background

In 2021, the Australian Government Department of Health commissioned a consortium of modelling groups to generate evidence assisting the transition from a goal of no community COVID-19 transmission to 'living with COVID-19', with adverse health and social consequences limited by vaccination and other measures. Due to the extended school closures over 2020-21, maximizing face-to-face teaching was a major objective during this transition. The consortium was tasked with informing school surveillance and contact management strategies to minimize infections and support this goal.

Methods

Outcomes considered were infections and days of face-to-face teaching lost in the 45 days following an outbreak within an otherwise COVID-naïve school setting. A stochastic agent-based model of COVID-19 transmission was used to evaluate a 'test-to-stay' strategy using daily rapid antigen tests (RATs) for close contacts of a case for 7 days compared with home quarantine; and an asymptomatic surveillance strategy involving twice-weekly screening of all students and/or teachers using RATs.

Findings

Test-to-stay had similar effectiveness for reducing school infections as extended home quarantine, without the associated days of face-to-face teaching lost. Asymptomatic screening was beneficial in reducing both infections and days of face-to-face teaching lost and was most beneficial when community prevalence was high.

Interpretation

Use of RATs in school settings for surveillance and contact management can help to maximize face-to-face teaching and minimize outbreaks. This evidence supported the implementation of surveillance testing in schools in several Australian jurisdictions from January 2022.

Perceived Benefits, Barriers, and Facilitators of a School District's COVID-19 Test to Stay Modified Quarantine Program in an Underresourced Community: December 2021

OBJECTIVES

Quarantine after exposure to COVID-19 has resulted in substantial loss of in-person learning in schools from prekindergarten through grade 12. Test to Stay (TTS), a strategy that limits the spread of SARS-CoV-2 while prioritizing in-person learning, requires substantial investment in resources. The objective of this study was to assess the perceived benefits, barriers, and facilitators of implementing TTS in an urban school district in the Midwest serving primarily Black or African American people with low income.

METHODS

In December 2021, we used a concurrent mixed-methods approach to understand perceived benefits, barriers, and facilitators of implementing TTS by combining quantitative analysis of telephone surveys conducted with parents (n = 124) and a qualitative inquiry involving key informants from the school district and local health department (n = 22). We analyzed quantitative data using descriptive statistics. We used thematic analysis to analyze qualitative data.

RESULTS

Quantitative findings showed that parents supported TTS because it was convenient (n = 83, 97%) and effective (n = 82, 95%) in keeping students learning in person (n = 82, 95%) and preventing the spread of COVID-19 (n = 80, 93%). Qualitative interviews with informants found that having a clear protocol and assigning staff to specified tasks allowed for successful TTS implementation. However, insufficient staffing and testing resources, parent mistrust of testing, and lack of communication from schools were perceived barriers.

CONCLUSION

The school community strongly supported TTS despite the many implementation challenges faced. This study emphasized the importance of ensuring resources for equitable implementation of COVID-19 prevention strategies and the critical role of communication.

Caregivers of Black and Latino/a/x Students and School Personnel Perspectives on School-Based SARS-CoV-2 Testing: Implications for Testing and Test-to-Stay Programs in K-12 Schools

BACKGROUND

"Test-to-stay" (TTS) is an effective approach for keeping students in school post-exposure to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). To prepare for school-based SARS-CoV-2 testing, we implemented formative research to gather perspectives on school-based testing among school personnel, as well as caregivers of Black and Latino/a/x students given systemic racism, existing school inequalities, and the disproportionate effect of COVID-19 on Black and Latino/a/x populations.

METHODS

We conducted in-depth interviews with caregivers of K-12 grade Black and Latino/a/x students and focus group discussions with K-12 school personnel. We described the forthcoming school-based SARS-CoV-2 testing program and explored potential benefits and concerns, including concerns about testing-related stigma and discrimination, particularly toward Black and Latino/a/x students, and implementation recommendations.

RESULTS

Perceived testing benefits included school community reassurance and preventing school outbreaks. Concerns included potential student anxiety, classroom disruption, inaccurate results, and limited information for caregivers. Some participants mentioned that testing-related stigma and discrimination could happen based on the testing selection process or results but not due to race or ethnicity. Participants provided numerous testing recommendations, including suggestions to prevent negative outcomes.

CONCLUSIONS

Participants believed that stigma and discrimination from SARS-CoV-2 testing is possible, although differential treatment based on race or ethnicity was not anticipated. Participants' narratives provide support for school-based testing and the testing component of TTS.

SARS-CoV-2 Screening Testing Programs for Safe In-person Learning in K-12 Schools

BACKGROUND

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) screening testing is a recommended mitigation strategy for schools, although few descriptions of program implementation are available.

METHODS

Kindergarten through 12th grade (K-12) students and staff practicing universal masking during the delta and omicron variant waves from five schools in Durham, North Carolina and eight schools in Kansas City, Missouri participated; Durham's program was structured as a public health initiative facilitated by school staff, and Kansas City's as a research study facilitated by a research team. Tests included school-based rapid antigen or polymerase chain reaction testing, at-home rapid antigen testing, and off-site nucleic acid amplification testing.

RESULTS

We performed nearly 5700 screening tests on more than 1600 K-12 school students and staff members. The total cost for the Durham testing program in 5 public charter K-12 schools, each with 500-1000 students, was $246 587 and approximately 752 h per semester; cost per test was $70 and cost per positive result was $7076. The total cost for the Kansas City program in eight public K-12 schools was $292 591 and required approximately 537 h in personnel time for school-based testing; cost per test was $132 and cost per positive result was $4818. SARS-CoV-2 positivity rates were generally lower (0-16.16%) than rates in the community (2.7-36.47%) throughout all testing weeks.

CONCLUSIONS AND RELEVANCE

Voluntary screening testing programs in K-12 schools are costly and rarely detect asymptomatic positive persons, particularly in universally masked settings.

CLINICAL TRIAL REGISTRATION

NCT04831866.

When schools were open for in-person teaching during the COVID-19 pandemic - the nordic experience on control measures and transmission in schools during the delta wave

BACKGROUND

Extensive measures to control spread of SARS-CoV-2 have led to limited access to education for millions of children and adolescents during the COVID-19 pandemic. Education and access to schools is vital for children and adolescents' learning, health, and wellbeing. Based on high vaccine uptake and low incidence levels, the Nordic countries (Denmark, Finland, Iceland, Norway and Sweden) decided to start the academic year 2021/22 with schools open for in-person teaching and moderate mitigation measures. We describe trends in SARS-CoV-2 infections and vaccination coverage among students during the first 12 weeks of the fall semester.

METHODS

In this multinational, retrospective, observational study, we have used surveillance and registry data from each of the Nordic countries to describe vaccine uptake (≥12 years), infection incidence (whole population) and transmission of SARS-CoV-2 among students. The study period, week 30 to 41 (Jul 26th - Oct 17th), represents the autumn semester from immediately before school started until fall break. In addition, we collected information on mitigation measures applied by the respective countries.

RESULTS

There were slight variations between the countries regarding existing infection prevention and control (IPC) measures, testing strategies and vaccination start-up among adolescents. All countries had high vaccine uptake in the adult population, while uptake varied more in the younger age groups. Incidence in the school-aged population differed between countries and seemed to be influenced by both vaccine uptake and test activity. Infection clusters among school-aged children were described for Denmark and Norway, and the number of clusters per week reflected the incidence trend of the country. Most events consisted of only 1-2 cases. Larger clusters appeared more frequently in the higher grades in Norway and in lower grades in Denmark.

CONCLUSION

Data from the Nordic countries indicate that vaccination of adults and adolescents, in addition to mitigation measures, enabled full in-person learning. As SARS-CoV-2 infection does not represent a severe medical risk for most children as previously thought, measures targeting this group should be carefully adjusted and kept at a minimum. Our data add to the evidence on incidence and transmission of SARS-CoV-2 among students in schools open for in-person teaching, and may be valuable for decision makers worldwide.

Trends in Risk Factors and Symptoms Associated With SARS-CoV-2 and Rhinovirus Test Positivity in King County, Washington, June 2020 to July 2022

IMPORTANCE

Few US studies have reexamined risk factors for SARS-CoV-2 positivity in the context of widespread vaccination and new variants or considered risk factors for cocirculating endemic viruses, such as rhinovirus.

OBJECTIVES

To evaluate how risk factors and symptoms associated with SARS-CoV-2 test positivity changed over the course of the pandemic and to compare these with the risk factors associated with rhinovirus test positivity.

DESIGN, SETTING, AND PARTICIPANTS

This case-control study used a test-negative design with multivariable logistic regression to assess associations between SARS-CoV-2 and rhinovirus test positivity and self-reported demographic and symptom variables over a 25-month period. The study was conducted among symptomatic individuals of all ages enrolled in a cross-sectional community surveillance study in King County, Washington, from June 2020 to July 2022.

EXPOSURES

Self-reported data for 15 demographic and health behavior variables and 16 symptoms.

MAIN OUTCOMES AND MEASURES

Reverse transcription-polymerase chain reaction-confirmed SARS-CoV-2 or rhinovirus infection.

RESULTS

Analyses included data from 23 498 individuals. The median (IQR) age of participants was 34.33 (22.42-45.08) years, 13 878 (59.06%) were female, 4018 (17.10%) identified as Asian, 654 (2.78%) identified as Black, and 2193 (9.33%) identified as Hispanic. Close contact with an individual with SARS-CoV-2 (adjusted odds ratio [aOR], 3.89; 95% CI, 3.34-4.57) and loss of smell or taste (aOR, 3.49; 95% CI, 2.77-4.41) were the variables most associated with SARS-CoV-2 test positivity, but both attenuated during the Omicron period. Contact with a vaccinated individual with SARS-CoV-2 (aOR, 2.03; 95% CI, 1.56-2.79) was associated with lower odds of testing positive than contact with an unvaccinated individual with SARS-CoV-2 (aOR, 4.04; 95% CI, 2.39-7.23). Sore throat was associated with Omicron infection (aOR, 2.27; 95% CI, 1.68-3.20) but not Delta infection. Vaccine effectiveness for participants fully vaccinated with a booster dose was 93% (95% CI, 73%-100%) for Delta, but not significant for Omicron. Variables associated with rhinovirus test positivity included being younger than 12 years (aOR, 3.92; 95% CI, 3.42-4.51) and experiencing a runny or stuffy nose (aOR, 4.58; 95% CI, 4.07-5.21). Black race, residing in south King County, and households with 5 or more people were significantly associated with both SARS-CoV-2 and rhinovirus test positivity.

CONCLUSIONS AND RELEVANCE

In this case-control study of 23 498 symptomatic individuals, estimated risk factors and symptoms associated with SARS-CoV-2 infection changed over time. There was a shift in reported symptoms between the Delta and Omicron variants as well as reductions in the protection provided by vaccines. Racial and sociodemographic disparities persisted in the third year of SARS-CoV-2 circulation and were also present in rhinovirus infection. Trends in testing behavior and availability may influence these results.

Comparison of COVID-19 Pandemic Waves in 10 Countries in Southern Africa, 2020-2021

We used publicly available data to describe epidemiology, genomic surveillance, and public health and social measures from the first 3 COVID-19 pandemic waves in southern Africa during April 6, 2020-September 19, 2021. South Africa detected regional waves on average 7.2 weeks before other countries. Average testing volume 244 tests/million/day) increased across waves and was highest in upper-middle-income countries. Across the 3 waves, average reported regional incidence increased (17.4, 51.9, 123.3 cases/1 million population/day), as did positivity of diagnostic tests (8.8%, 12.2%, 14.5%); mortality (0.3, 1.5, 2.7 deaths/1 million populaiton/day); and case-fatality ratios (1.9%, 2.1%, 2.5%). Beta variant (B.1.351) drove the second wave and Delta (B.1.617.2) the third. Stringent implementation of safety measures declined across waves. As of September 19, 2021, completed vaccination coverage remained low (8.1% of total population). Our findings highlight opportunities for strengthening surveillance, health systems, and access to realistically available therapeutics, and scaling up risk-based vaccination.

Test-to-Stay Implementation in 4 Pre-K-12 School Districts

OBJECTIVES

Globally, coronavirus disease 2019 (COVID-19) has affected how children learn. We evaluated the impact of Test to Stay (TTS) on secondary and tertiary transmission of severe acute respiratory syndrome coronavirus 2 and potential impact on in-person learning in 4 school districts in the United States from September 13 to November 19, 2021.

METHODS

Implementation of TTS varied across school districts. Data on index cases, school-based close contacts, TTS participation, and testing results were obtained from 4 school districts in diverse geographic regions. Descriptive statistics, secondary and tertiary attack risk, and a theoretical estimate of impact on in-person learning were calculated.

RESULTS

Fifty-one schools in 4 school districts reported 374 coronavirus disease COVID-19 index cases and 2520 school-based close contacts eligible for TTS. The proportion participating in TTS ranged from 22% to 79%. By district, the secondary attack risk and tertiary attack risk among TTS participants ranged between 2.2% to 11.1% and 0% to 17.6%, respectively. Nine clusters were identified among secondary cases and 2 among tertiary cases. The theoretical maximum number of days of in-person learning saved by using TTS was 976 to 4650 days across jurisdictions.

CONCLUSIONS

TTS preserves in-person learning. Decisions to participate in TTS may have been influenced by ease of access to testing, communication between schools and families, testing logistics, and school resources. Tertiary attack risk determination became more complicated when numbers of close contacts increased. Minimizing exposure through continued layered prevention strategies is imperative. To ensure adequate resources for TTS, community transmission levels should be considered.

High Sensitivity and NPV for BinaxNOW Rapid Antigen Test in Children at a Mass Testing Site during Prevalent Delta Variant Period

SARS-CoV-2 continues to develop new, increasingly infectious variants including delta and omicron. We evaluated the efficacy of the Abbott BinaxNOW Rapid Antigen Test against Reverse Transcription PCR (RT-PCR) in 1,054 pediatric participants presenting to a high-volume Coronavirus Disease 2019 (COVID-19) testing site while the delta variant was predominant. Both tests utilized anterior nares swabs. Participants were grouped by COVID-19 exposure and symptom status. 5.2% of samples tested positive by RT-PCR for SARS-CoV-2. For all participants, sensitivity of the BinaxNOW was 92.7% (95% CI 82.4%-98.0%), and specificity was 98.0% (95% CI 97.0%-98.8%). For symptomatic participants, positive predictive value (PPV) was 72.7% (95% CI 54.5%-86.7%) and negative predictive value (NPV) was 99.2% (95% CI 98.2%-100%). Among asymptomatic participants, PPV was 71.4% (95% CI 53.7%-85.4%) and NPV was 99.7% (95% CI 99.0%-100%). Our reported sensitivity and NPV are higher than other pediatric studies, potentially because of higher viral load from the delta variant, but specificity and PPV are lower. IMPORTANCE The BinaxNOW rapid antigen COVID-19 test had a sensitivity of nearly 92% in both symptomatic and asymptomatic children when performed at a high-throughput setting during the more transmissible delta variant dominant period. The test may play an invaluable role in asymptomatic screening and keeping children safe in school.

Utility of a Test-to-Return Strategy to Identify Individuals With Coronavirus Disease 2019 (COVID-19) in the Prekindergarten Through Grade 12 School Setting-District of Columbia, January 2022

The highly transmissible severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant led to increased hospitalizations, staffing shortages, and increased school closures. To reduce spread in school-aged children during the Omicron peak, the District of Columbia implemented a test-to-return strategy in public and public charter schools after a 2-week break from in-person learning.

School Masking Policies and Secondary SARS-CoV-2 Transmission

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.

Severe Acute Respiratory Syndrome Coronavirus 2 Infections in Children

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections in children generally have milder presentations, but severe disease can occur in all ages. MIS-C and persistent post-acute COVID-19 symptoms can be experienced by children with previous infection and emphasize the need for infection prevention. Optimal treatment for COVID-19 is not known, and clinical trials should include children to guide therapy. Vaccines are the best tool at preventing infection and severe outcomes of COVID-19. Children suffered disproportionately during the pandemic not only from SARS-CoV-2 infection but because of disruptions to daily life, access to primary care, and worsening income inequalities.

A Test-to-Stay Modified Quarantine Program for COVID-19 in Schools

BACKGROUND AND OBJECTIVES

Mandatory quarantine upon exposure to coronavirus disease 2019 (COVID-19) results in a substantial number of lost days of school. We hypothesized that implementation of a state-wide test-to-stay (TTS) program would allow more students to participate in in-person learning, and not cause additional clusters of COVID-19 cases due to in-school transmission.

METHODS

For the 2020-2021 academic year, Massachusetts implemented an opt-in TTS program, in which students exposed to COVID-19 in school are tested each school day with a rapid antigen test. If negative, students may participate in school-related activities that day. Testing occurs daily for a duration of 7 calendar days after exposure. Here, we report the results from the first 13 weeks of the program.

RESULTS

A total of 2298 schools signed up for TTS, and 504 167 individuals out of a total population of 860 457 consented. During the first 13 weeks with complete data, 1959 schools activated the program at least once for 102 373 individual, exposed students. Out of 328 271 tests performed, 2943 positive cases were identified (per person positivity rate, 2.9%, 95% confidence interval, 2.8-3.0). A minimum of 325 328 and a maximum of 497 150 days of in-person school were saved through participation in the program.

CONCLUSIONS

Daily, rapid on-site antigen testing is a safe and feasible alternative to mandatory quarantine and can be used to maximize safe in-person learning time during the pandemic.

Replacing quarantine of COVID-19 contacts with periodic testing is also effective in mitigating the risk of transmission

The quarantine of identified close contacts has been vital to reducing transmission rates and averting secondary infection risk before symptom onset and by asymptomatic cases. The effectiveness of this contact tracing strategy to mitigate transmission is sensitive to the adherence to quarantines, which may be lower for longer quarantine periods or in vaccinated populations (where perceptions of risk are reduced). This study develops a simulation model to evaluate contact tracing strategies based on the sequential testing of identified contacts after exposure as an alternative to quarantines, in which contacts are isolated only after confirmation by a positive test. The analysis considers different number and types of tests (PCR and lateral flow antigen tests (LFA)) to identify the cost-effective testing policies that minimize the expected infecting days post-exposure considering different levels of testing capacity. This analysis suggests that even a limited number of tests can be effective at reducing secondary infection risk: two LFA tests (with optimal timing) avert infectiousness at a level that is comparable to 14-day quarantine with 80–90% adherence, or equivalently, 7–9 day quarantine with full adherence (depending on the sensitivity of the LFA test). Adding a third test (PCR or LFA) reaches the efficiency of a 14-day quarantine with 90–100% adherence. These results are robust to the exposure dates of the contact, test sensitivity of LFA and alternative models of viral load evolution, which suggests that simple testing rules can be effective for improving contact tracing in settings where strict quarantine adherence is difficult to implement.

Pediatric Emergency Department Visits Before and During the COVID-19 Pandemic - United States, January 2019-January 2022

Emergency departments (EDs) in the United States remain a frontline resource for pediatric health care emergencies during the COVID-19 pandemic; however, patterns of health-seeking behavior have changed during the pandemic (1,2). CDC examined changes in U.S. ED visit trends to assess the continued impact of the pandemic on visits among children and adolescents aged 0-17 years (pediatric ED visits). Compared with 2019, pediatric ED visits declined by 51% during 2020, 22% during 2021, and 23% during January 2022. Although visits for non-COVID-19 respiratory illnesses mostly declined, the proportion of visits for some respiratory conditions increased during January 2022 compared with 2019. Weekly number and proportion of ED visits increased for certain types of injuries (e.g., drug poisonings, self-harm, and firearm injuries) and some chronic diseases, with variation by pandemic year and age group. Visits related to behavioral concerns increased across pandemic years, particularly among older children and adolescents. Health care providers and families should remain vigilant for potential indirect impacts of the COVID-19 pandemic, including health conditions resulting from delayed care, and increasing emotional distress and behavioral health concerns among children and adolescents.