Impact of Test To Stay on Transmission of SARS-CoV2 in K-12 schools, Lake County, Illinois

The Lake County Health Department and Community Health Center was established in Lake County, Illinois, in 1956. It is a public health accredited department and a Federally Qualified Health Center (FQHC). With a budget of approximately $80 million the Health Department supports over 50 programs. Around 900 professionals assist the Health Department's mission to promote the health and well-being of all who live, work, and play in Lake County. Lake County is the third-most populous county in Illinois, sitting just north of Cook County and the City of Chicago, with a population of close to 700,000. In 2019, according to the U.S. Census Bureau, 60.6 % of the population was White alone; 22.4% Hispanic or Latino; 7.5% Black or African American alone, and 8.4% Asian alone. About 7% of the population lived in poverty. Of those patients the Health Department served in fiscal year 2021, 24% were uninsured and over 60% were insured through Medicaid. Sixty percent of Health Department patients are Hispanic or Latino and 17% are Black or African American.

Like most communities in the United States, the COVID-19 pandemic substantially impacted Lake County's education system, the children, and families it serves. Due to school closures and quarantine, there was a substantial loss of in-person learning days for children. Concerned about the impact on students both psychologically and academically as well as the economic and emotional impact on their families, the Health Department sought ways in which to keep children in schools while staying protected against COVID-19.

After State approval, in August of 2021, the Health Department worked with participating schools within the county to implement a "Test to Stay" (TTS) strategy. TTS allows unvaccinated students, teachers and staff, with a mask-on-mask school exposure to COVID-19 to remain in school and participate in school-related activities if they remain asymptomatic, maintain consistent mask wearing, and undergo SARS-CoV-2 testing on days 1,3, 5 and 7 after exposure, and test negative. The program goal was to evaluate the impact of TTS on the secondary and tertiary transmission of COVID-19 by type of school exposure and grade level.

From August 9October 29, 2021, 90 schools (K12) reported 258 cases of COVID-19. Among 1,035 students and staff close contacts enrolled in TTS, the secondary attack rate was 1.5%. Assuming eight missed school days for every 10-day quarantine, 8,152 in-person learning days were saved among close contacts. The work of Health Department showed that implementation of TTS, with layered prevention strategies, did not lead to further spread within the K12 school setting and allowed students to safely sustain in-person learning.

The Health Department was able to successfully implement this strategy because of the strong, trusting relationships with County schools that have been maintained throughout the pandemic. The Health Department Communicable Disease program has a four-person team that liaises with schools and helps guide them through the changing pandemic landscape. In addition, weekly calls have been held with County superintendents since the beginning of the pandemic, to update them on the latest guidance and answer questions. Lake County schools that met eligibility requirements were encouraged by the Health Department to implement the TTS program and were coached along the way by Health Department staff. Once schools enrolled in the TTS program, school-based close contacts could participate in TTS if exposures were within 3ft; masks were worn by both the index case and the contact; and parental consent was obtained. Close contacts with unmasked exposure within 6 ft of a case were not eligible for TTS and were required to quarantine. Those who were fully vaccinated or diagnosed with COVID-19 in the past 90 days were not required to quarantine. TTS participants were required to obtain a Nucleic Acid Amplification Test (NAAT) or antigen test at school or an off-campus location. While participants with negative test results were permitted to ride the bus and attend in-person learning and school-based extracurriculars, including sports (with correct mitigation strategies in place), they were required to quarantine for 14 days from all non-school-sanctioned activities.

 The Centers for Disease Control and Prevention (CDC) published the findings of the Health Department's study in a December Morbidity and Mortality Weekly Report (MMWR) (December 17, 2021). It contributed to adoption of this strategy by the CDC and by President Biden.

TTS is a resource-intensive strategy that may be difficult for schools to implement if they do not have the resources for robust contact tracing, increased administrative demands, and availability of COVID-19 tests and space. For example, low-resource schools might lack space for physical distancing during lunch, resulting in unmasked exposures within 6 feet, which would disqualify students from TTS eligibility, necessitating home quarantine. The Health Department piloted embedding a contact tracer into a school district struggling to implement TTS during this study. The contact tracer was able to facilitate contact tracing, inform parents, and provide public health recommendations. It will be important for schools with limited resources to advocate for staffing and access to testing supplies for TTS so that these vulnerable students may stay in school and their parents don't have to take time off from work.

www.lakecountyil.gov 

The Lake County Health Department identified that lost in-person learning days detrimentally impacted the health and well-being of students and parents very early in the pandemic. The school closing, social distancing, and quarantine caused disruptions to daily routines that are essential to a child's welfare. The disruptions also caused many parents/guardians financial hardships. For children and adolescents with mental health needs, school closures also meant a lack of access to the educational and emotional resources obtained through schools. Declining test scores revealed the extent to which students in virtual” learning did not absorb learning. The Health Department was committed to find ways where children could stay in school for their overall health.

The target population affected by this problem is 5–18 years old students (122,352) and school staff (11,672) attending or working at K–12 schools in Lake County, Illinois. During the study period, the 90 Lake County schools that implemented TTS and reported cases to LCHD represented 53.7% (6,267) of staff members and 53.4% (65,384) of students in Lake County public/charter schools.* The 1,035 student close contacts participating in TTS had a median age of 10 years old (3-18 years old), 65.3% White, 6.9% Asian, 3.6% Black, and 23.5% other/unknown. More than half (60.5%) were non-Hispanic/Latino and 10.1 % Hispanic, and 29.4% other/unknown ethnicity.

At the time of the study, B.1.617.2 (Delta) variant was prominent and known to be highly aggressive and contagious, with high viral loads, more potential for severe illness among unvaccinated individuals, and possible existing substantial transmission in fully vaccinated people. The new Delta variant led to concerns in the community that schools were unsafe and sites of widespread COVID-19 transmission even with effective mitigation strategies in place.  While schools had implemented universal masking, and physical distancing, improved hand hygiene and cleaning practices, and worked together with health departments on contact tracing, routine SARS-CoV-2 testing is not regularly implemented to provide added protection.

In the Spring of 2021, LCHD conducted a pilot project looking at limiting the quarantine of students with masked exposures to a COVID-19 case within 3 feet in a classroom setting (vs. the previous threshold of 6 feet). Even though the study period was short (2 weeks) and consisted of a small sample size, it showed that there was no secondary transmission in the classroom when mitigation was followed (unpublished). The layered mitigation schools had in place kept the spread of COVID-19 in the classroom low. Simply shortening the distance for the definition of a close contact helped more students stay in school, and benefit from more in-person learning days. 

This pilot project facilitated the development of the TTS strategy in Lake County. While TTS addresses health inequities by providing students the opportunity to remain in school as an alternative to quarantine, low resourced schools struggled implementing TTS for a number of reasons. TTS requires many resources that some schools may not have available such as robust contact tracing and ample testing resources. The Health Department worked with superintendents early to link schools to free, state-funded COVID-19 testing programs (i.e., Shield) to ease the burden on school staff. Additionally, the Health Department developed a testing coordinator role, whereby the coordinator would assist schools in completing the necessary documentation and training. The Health Department also worked directly with the Illinois Department of Public Health (IDPH) to distribute rapid antigen kits (at no cost) to schools in need of testing resources. Finally, noting the disparity in the quality of TTS implementation, the Health Department offered a program where a contact tracer was embedded within a school district that needed help. Health Department school liaisons developed strong relationships with school nurses and superintendents to address any issues that arose immediately.

TTS is an effective alternative to quarantine that increases in-person learning days; but also, highlights the need to bring appropriate resources to schools. Many schools cannot currently shoulder the associated costs for such a resource-intensive strategy despite its many benefits. Currently, a small number of jurisdictions across the country have developed and implemented TTS. With its innovative approach, the Lake County Health Department was one of the earliest to implement TTS, starting on August 9, 2021. We collaborated with the CDC and the Illinois Department of Public Health (IDPH) to provide data to inform federal and state policies. Hosted by CDC, the Health Department also presented at two Community of Practice presentations to share its work. Additionally, the Health Department provided its TTS strategy protocols and supplementary documentation to health departments across the country looking to implement TTS. The Lake County Health Department was featured alongside other TTS implementors in a CNN piece on October 19, 2021, covering the ongoing CDC evaluation of TTS.

The Lake County Health Department developed its TTS strategy on evidence-based practices of multiple studies all showing that layered mitigation, including masking, led to low transmission of SARs-CoV2 in classrooms^†§¶. And, as described in a Lancet article which showed the non-inferiority of daily testing and isolation**.

* Regional Office of Education Lake County, IL. School Directory-Enrollement (sic) 2021–2022.xlsx. Libertyville, IL: Regional Office of Education; 2021. https://e8c2718a-8f7f-4b7f-929b-1ecf15dd5e72.filesusr.com/ugd/a9e3eb_a559da92937a45d4871b397c2a805b97.pdf

† Hershow RB, Wu K, Lewis NM, et al. Low SARS-CoV-2 transmission in elementary schools—Salt Lake County, Utah, December 3, 2020–January 31, 2021. MMWR Morb Mortal Wkly Rep 2021;70:442–8. https://www.cdc.gov/mmwr/volumes/70/wr/mm7012e3.htm?s_cid=mm7012e3_w

§ Zimmerman KO, Akinboyo IC, Brookhart MA, et al. Incidence and secondary transmission of SARS-CoV-2 infections in schools. Pediatrics 2021. Epub March 1, 2021. https://doi.org/10.1542/peds.2020-048090external icon

¶ Falk A, Benda A, Falk P, Steffen S, Wallace Z, Hoeg TB. COVID-19 cases and transmission in 17 K–12 schools—Wood County, Wisconsin, August 31–November 29, 2020. MMWR Morb Mortal Wkly Rep 2021;70:136–40 https://doi.org/10.15585/mmwr.mm7004e3external icon

** Daily testing for contacts of individuals with SARS-CoV-2 infection and attendance and SARS-CoV-2 transmission in English secondary schools and colleges: an open-label, cluster-randomised trial. Lancet 2021;398:1217–29. https://doi.org/10.1016/S0140-6736(21)01908-5

The program objective was to evaluate the impact of TTS on the secondary and tertiary transmission of COVID-19 by type of school exposure and grade level. An additional aim was to measure the number of in-person learning days saved.

To achieve this goal, the Health Department developed a TTS study protocol with review and feedback provided by the CDC and IDPH. The Health Department reached out to all Lake County superintendents, inviting them to participate. Schools that both met eligibility criteria and expressed interest in implementation for Fall 2021, had their school nurses attend a Health Department webinar training front line staff on how to implement the TTS protocol. The Health Department provided schools with supplemental materials including two template letters (one for TTS-eligible students and staff, the second for students and staff needing to quarantine); a quarantine infographic; a data collection tool; and a screening checklist for school nurses to quickly determine who is eligible for TTS. The Health Department developed a Research Electronic Data Capture (version 11.2.6; IDPH) (RedCap) reporting tool and trained school nurses on how to use it to report COVID-19 positive cases and close contacts. It was required that all participating schools report in school COVID-19 positive cases using the RedCap system. School administration completed a survey sharing what in-school mitigation strategies (including universal masking) were implemented and attesting that they met the criteria necessary to implement TTS. The TTS strategy was shared with Lake County residents via an informational YouTube video shared on the Health Department social media sites and website.

Health Department contact tracers were trained on the TTS protocol and the associated public health guidance for interviewing school staff, nurses, and parents. In addition, they received multiple trainings on standardized data entry and the completion of surveillance records. Health Department staff were equipped with messaging on TTS to ensure that calls, emails, and questions were answered or directed to the correct team member.

The TTS practice is still ongoing; however, the timeframe analyzed was from August 9, 2021–October 29, 2021.  The Health Department is grateful for all the partnerships during this period that made its success possible. The CDC COVID-19 Response Team deployed a team of epidemiologists who worked on site and remotely for more than six weeks to help clean, manage, and analyze data. The guidance and expertise that IDPH provided during weekly calls with CDC and the Health Department was vital in the program's implementation. School superintendents offered feedback on their implementation of TTS and asked clarifying questions during weekly calls hosted by Health Department liaisons.

The Health Department's Medical Epidemiologist was the primary investigator of this study. Under her leadership, the team developed, planned, and implemented the TTS strategy in Lake County, IL. After all schools were invited to participate in TTS, Health Department staff evaluated school applications and enrolled schools that were eligible. Health Department staff worked with school staff to implement the strategies correctly and answer any questions. Health Department staff collaborated with the CDC for analysis of the data.

 All schools were given the opportunity to implement TTS if they met eligibility criteria. However, during the implementation, it became clear that some schools could not consider TTS as an option due to lack of space for physical distancing during lunch. This would result in unmasked exposures within 6 feet, which would disqualify students from TTS eligibility, necessitating home quarantine. Health Department community liaisons worked with some of these schools to identify creative alternatives for lunch so that students would not be automatically disqualified. The Health Department is reviewing the TTS strategy with IDPH after identifying this issue to see if in the coming semester close contacts identified from lunch exposures could be included in TTS.

By allowing all schools who met eligibility criteria to participate, we found that among the 90 TTS schools reported in this study, 25.6% participated in a subsidized lunch program, compared with 38.1% of schools that did not implement TTS. Our hope is  to enroll more schools into the TTS program. The Health Department school liaisons have and will continue to reach out to schools to encourage implementation of TTS. The publication of our findings in the MMWR supports this strategy and its outcomes. Since publication, more schools in Lake County have expressed interest in participating.

Health Department costs associated with implementation include staffing five teams of 3-7 contact tracers each led by a team lead and overseen by two coordinators who were trained and specialized in working with schools implementing TTS. Additionally, four community liaisons facilitated data-sharing between schools and contact tracers. As the number of TTS schools grew, more teams of contact tracers were reassigned from routine case investigation/contact tracing and trained on TTS school exposure investigations. In addition, Health Department staff collected data and reviewed the testing, TTS, and quarantine recommendations provided by school nurses. The contact tracers were employed under a $3 million grant awarded by IDPH for six months.

The cost for a school to implement TTS is unknown. The Illinois State Board of Education provided a large amount of money to schools to install and implement mitigation strategies to keep children/staff safe. Schools used some of these funds to hire contact tracers or contract with a third-party medical/laboratory group to assist with administering and reporting test results to parents, the Health Department, and IDPH. Schools that may not have had the forethought to use the funding for staff to implement TTS, had difficulty in keeping up with the number of cases as the disease burden increased in the community. IDPH provided free testing resources to all Illinois schools through the University of Illinois Shield Program (saliva test) and by contracting with Abbott to purchase and distribute antigen test kits to schools via local health departments. In a survey provided to school nurses, a majority of respondents recommended 1-2 full-time staff for each school dedicated to implementing TTS. This includines identification of cases, contact tracing to identify close contacts, testing, documenting, reporting results, informing parents, and collecting data and providing it to the Health Department. If we were to estimate the cost of 1-2 full-time staff, we could take the hourly cost of one Health Department contact tracer ($23/hr) and estimate that $24,000–$48,000 were needed to employ the staff necessary to implement TTS for a school semester (6 months). However, please note, some schools utilized other staff from other programs/departments (i.e., athletics, school administration) to assist in TTS rather than hiring.

The objective was to evaluate the impact of TTS on the secondary and tertiary transmission of COVID-19 by type of school exposure and grade level. During August 9October 29, 2021, 90 schools implementing TTS (representing 53.7% [6,267] of staff members and 53.4% [65,384] of students in Lake County public/charter schools) reported 258 COVID-19 cases. No secondary cases among staff members or teachers were identified during the 12-week evaluation period. Among 1,068 close contacts eligible for TTS, 1,035 (97%) participated. Of 1,035 students and staff members enrolled in TTS, secondary attack risk was 1.5% (16 TTS students received a positive SARS-CoV-2 test result). The most likely locations of COVID-19 exposure among TTS participants were school buses (56%), classrooms (32%), and school-sanctioned sports (7%); the secondary attack risks were 1.5%, 0.6%, and 6.5%, respectively. Secondary transmission was lowest in elementary schools (1.1%), followed by middle schools (1.3%), and high schools (4.9%). Assuming a maximum of eight missed school days for every 10-day quarantine, an upper limit estimate of 8,152 in-person learning days were saved among close contacts. There was no evidence of transmission from school-based close contacts who subsequently received a positive SARS-CoV-2 test result while in TTS, although nine tertiary cases were identified among household contacts, four of whom were fully vaccinated.

School nurses and/or designees identified and reported case and close contact information to the Health Department via Research Electronic Data Capture (version 11.2.6; IDPH) (RedCap). Health Department contact tracers interviewed parents of close contacts for additional details and to identify exposures outside of school. Data were supplemented with the Salesforce contact tracing management system, Illinois' National Electronic Disease Surveillance System (I-NEDSS), and the Illinois state vaccination registry. Data were analyzed with SAS Programming (9.4). Among TTS participants, secondary cases were defined as contacts who received a positive SARS-CoV-2 test result within 14 days after exposure to an index patient. Secondary attack risk was defined as number of TTS participants who received a positive SARS-CoV-2 test result within 14 days after exposure divided by total number of TTS close contacts. Tertiary cases were defined as contacts who received a positive SARS-CoV-2 test result within 14 days after exposure to a secondary case.

Implementation of TTS with multipronged prevention strategies prevented further spread within K12 schools and allowed students to safely sustain in-person learning. These findings highlight the usefulness of TTS to limit school-based transmission and sustain in-person learning. Secondary transmission risk to students exposed during school-sanctioned sports was higher than that associated with classroom or school bus exposures. However, a smaller number of TTS participants were exposed in sports. The finding from this analysis demonstrates that with multiple prevention strategies, including universal masking, the classroom and buses are locations of low risk for secondary transmission. The Health Department is currently reviewing and updating the TTS protocol based on current findings. In settings where appropriate mask usage occurs, those individuals would no longer be considered close contacts. The TTS strategy may be better utilized in locations of high risk where improper or absence of mask usage occurs. It may help rapidly identify those who test positive and prevent further spread while permitting students who continue to test negative to remain in school, thereby further reducing need of quarantine among students. The goal is to modify and implement an updated TTS strategy for the Spring 2021 semester.

The TTS strategy works in a setting of  multipronged mitigation strategies. It is a resource-intensive strategy. In Illinois, school nurses and designated staff are now required to conduct school-based contact tracing for individual cases and appropriately exclude students or apply TTS to mitigate potential spread of COVID-19 in schools (IDPH guidance*, and the Governor's Executive Order**).

A limitation we identified in our analysis was inequity in school districts' staffing and testing resources. This may have introduced selection bias because only schools with sufficient resources offered TTS. Also, high-resource schools may have more staffing capacity and physical spacing to apply prevention strategies (e.g., distancing students). These additional resources could have resulted in low transmission levels that are not generalizable to low-resource schools. The lack of space for physical distancing during lunch, resulting in unmasked exposures within 6 feet, would disqualify students from TTS eligibility, necessitating home quarantine. The Health Department is currently reviewing lunch exposure data. If the secondary transmission risk appears relatively low, close contacts exposed during lunch may be permitted to participate in TTS, thereby expanding the TTS strategy in schools that have struggled with seating kids for lunch. Additionally, several low-resource schools have implemented TTS but may not be reporting cases and close contacts in a timely fashion due to staffing capacity issues. The Health Department is working to identify these schools and will advocate for additional staff.

Clear communication with school partners and the community is key in the success of TTS. School partners were engaged early, trained, and provided supplemental documents to implement the TTS in schools. The strategy was shared with the public via a YouTube video posted on social media that explained TTS. An infographic was created to show what TTS looked like in relation to the other quarantine options and was shared with schools and the public. The data collection and analysis were due in large part to the state funding provided to maintain a contact tracing workforce. With the possibility of losing funding after the first quarter of 2022, the Health Department will likely no longer be able to collect data on TTS and analyze. Rather, prioritization will be given to supporting schools so that they can become more independent in their contact tracing, school exclusion, and TTS implementation. The Health Department hopes to transition to a consultant role for schools to collaborate with in complex situations or during outbreaks that may occur. In-school testing has been largely funded by IDPH and Illinois State Board of Education. Hopefully, funding will continue and allow schools to maintain the TTS strategy for as long as it is needed. A cost/benefit analysis was not performed on Lake County's TTS strategy and should be considered. However, with over 8,000 in-school days saved, all school staff have agreed that it is a great strategy to keep kids in schools.

The pandemic continues to evolve in the United States with emergence of new strains and continued pushes toward vaccination. As public guidance moves towards endemicity, prevention in schools will evolve. TTS has shown to be a great alternative to quarantine in schools. The Lake County Health Department will continue to use a data-driven approach as it expands eligibility for TTS to more students when exposed in other situations. Continued and future access to in-school testing will empower schools to rapidly identify and isolate those infected with COVID-19 and monitor close contacts for COVID-19 via frequent testing.

*IDPH guidance: https://dph.illinois.gov/covid19/community-guidance/school-guidance/school-guidance-faqs.html 

**Governor's Executive Order:  https://www.illinois.gov/government/executive-orders/executive-order.executive-order-number-25.2021.html