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

For the 2021–2022 academic year, Massachusetts DESE offered 3 testing programs to any type (private, public, or charter) of K–12 school: a weekly pooled PCR screening testing program, on-site diagnostic testing with an antigen test for symptomatic individuals, and TTS with daily rapid antigen testing. TTS is offered as an alternative to mandatory at-home quarantine for asymptomatic, unvaccinated individuals in Massachusetts who attend a school that opted into the state program, who are exposed to COVID-19 in schools, on school buses, or in school-sanctioned extracurricular programs. The programs are funded by the Epidemiology Laboratory Capacity reopening schools grant from the American Rescue Plan Act of 2021. The state contracts with a primary health care company to coordinate all aspects of the program in collaboration with infrastructure at the individual schools, including school nursing staff. Test kits, staffing (specimen collection, program coordination, etc), courier services, and other supports are provided at no cost to participating schools. School nurses collaborate with the contracted health care company and other district colleagues to develop and implement the testing program, and sometimes direct and run the program.

If a school signs up to offer the program, parents must opt-in and provide signed consent before a student is eligible to participate. Those who decline to participate are required to stay home from school and quarantine for at least 7 days following any in-school close contact, per state protocols, if not fully vaccinated. In accordance with the Center for Disease Control and Prevention and state-wide recommendations during the study period, vaccinated individuals, who would not be subject to quarantine, were not eligible for participation in TTS, as the program would not impact their ability to participate in in-person learning. A state-wide Clinical Laboratory Improvement Amendment certificate of waiver is in effect that permits antigen testing within the school setting, and standing orders are provided by the contracted health care companies.

For those that opt-in, asymptomatic individuals identified as in-school close contacts are offered daily rapid antigen testing. State guidance defines an in-school exposure as being within 3 feet of distance for >15 minutes if both masked, or 3–6 feet of distance if 1 or both are unmasked, during the infectious period of an individual who tests positive for COVID-19. The exposure period is defined as 48 hours before symptom onset (or date of positive test if no symptoms develop) until time of isolation. Individuals in the TTS protocol are tested every school day plus any weekend days in which they are involved in a school-sponsored activity, through 7 calendar days after the last known exposure date. If the antigen test is negative, the individual is able to participate in school-related activities, including classroom learning, riding the bus, and extracurricular activities on that date. Individuals with exposures outside of school are not eligible for TTS and must quarantine. Those who develop symptoms during the TTS period are removed from the program, recommended to receive confirmatory PCR-based testing, and begin to isolate at the time of symptom onset. Students may participate in the program multiple times if they are identified as an in-school close contact on multiple occasions, but only data from the first entry was included in the analysis.

Data from the first 13 weeks (9/12/2021–12/10/2021) of the program obtained from the contracted health care company included: number of enrolled schools, number of consented individuals and their demographic data, number of eligible individuals, number of schools activating the TTS program due to an in-school exposure, number of individuals tested, and number of positive and negative tests. Data obtained from DESE included demographic data from public schools across the state and schools participating in the TTS program. Data obtained from the state department of Health and Human Services included vaccination rates at different points in the study period and estimates of program costs. Data are entered at the school level with electronic queries to avoid errors in entry, and the state contact tracing program provided quality-control by following up on all positive cases reported.

We define cases as follows: the index individual with COVID-19 in the school is considered the primary case, the individual exposed and testing positive in the TTS program is a secondary case, and resulting cases from the secondary case are considered tertiary cases. The TTS program positivity rate is calculated in multiple ways: weekly per person positivity rate is the total number of positive tests divided by all unique individuals reported to have been tested that week; if a student is tested over 2 school weeks (eg, TTS initiated in the middle of the school week), then the individual is only counted during their first week of participation if they test negative, or on the week they test positive if they test positive; overall per person positivity rate is the number of individuals who tested positive within the program divided by the number of individuals who participated in the program over the 13 week study period; the per test positivity rate is the total number of positive tests divided by all of the tests performed. Invalid tests are removed from denominators for analysis. Positivity rates stratified by vaccine-eligibility (age ≥12 years was eligible for vaccination during the study period) are also reported.

The daily distribution of positive cases following program entry after exposure is reported as a continuous measure, as is the cumulative percent of individuals testing positive by day of program entry.

Due to unreliable reporting of negative tests, the number of days of school saved is calculated in 2 ways, and a range of potential estimates is presented. The minimum number of days saved is calculated as the total number of negative tests reported to the testing company (as each negative test allows a student to attend school that day). The maximum number of days saved is the number of unique students enrolled in the program who never had a positive test, multiplied by 5 to represent the maximum number of school days the student would have needed to quarantine without the TTS program, assuming the first test occurred on the day following the classroom exposure and the student remained asymptomatic during the TTS duration.

To estimate the maximum number of in-school tertiary transmissions resulting from participation in the TTS program, we calculated the number of times in which at least 1 individual in the same grade of the same school was identified as positive during the 2-week period following a secondary case. This is an upper-bound estimate, because the positive cases may have been unrelated.

Data were analyzed in Microsoft Excel using simple descriptive statistics and stratified by vaccination eligibility. As no individually identifiable data were collected, this study does not constitute human subjects research.

An iterative process of feedback between school district superintendents, school nurses, DESE, and the contracted health care company is maintained to ensure problems are addressed in real time, and we report results of the process.

Demographic data of public school students across the state, participating schools, and consented individuals are presented in Table 1; public schools that enrolled closely mirror state-wide demographics. Among those that consented, 85.1% reported White race, 6.4% reported African American race, 7.8% reported Asian race, and 15.6% identified as Hispanic. In total, 2298 schools out of 2414 potentially eligible K–12 schools across Massachusetts (95.2%) signed up to participate in the TTS program with a total enrollment of 860 457 students (this includes those who were vaccinated and therefore not eligible). Of the 860 457 students, 504 167 individuals (58.6% of all students at participating schools) consented to participate in the TTS program. During the program, the overall COVID-19 vaccination rate in Massachusetts increased from 73% with 1 dose on September 14^th, 2021 to 83% with 1 dose on December 14^th, 2021. The overall cost of all school-based testing programs to the state for the fall of 2021 is estimated to be $60 000 000, inclusive of test kits and materials, contracted labor, laboratory processing, couriers, software, and all other costs.

In total, 1959 schools activated the TTS program at least once, and 328 271 tests were reported from 102 373 unique individuals exposed to COVID-19 in school. The program underwent a scale-up during the beginning; after feasibility, safety, and value was demonstrated in the early weeks of the program, and additional schools and students opted-in. Increase in participation was particularly apparent in the 2 weeks following Thanksgiving, in which the number of participants and number of positive cases increased, both likely caused by increased community spread after holiday gatherings. Many parents did not provide consent for students to participate in the program until they were exposed to COVID-19, considered a close contact, and were faced with the option of TTS or quarantine.

A summary of all secondary cases, per person positivity rate, and days of school saved by the program per week is presented in Table 2. Over the first 13 weeks with complete data, 68 tests were invalid, 2943 positive cases were identified out of 328 271 valid tests performed. The overall per person positivity rate was 2.9% (95% confidence interval [CI] 2.8–3.0) and per test positivity rate was 0.9% (95% CI 0.9). The state asymptomatic pooled screening program over the same time found an overall individual positivity rate of approximately 0.2% (2795 of 1 700 000), which increased from 0.2% in the first week to 0.5% in the final week of the study period.

During the 13-week study period, the minimum number of school days saved, as calculated based on the number of reported negative tests, was 321 781. The maximum number of days saved, assuming participating individual who did not test positive avoided 5 days of quarantine, is 492 315.

The program was initiated more frequently for younger students not yet eligible for vaccination during the study period, but overall positivity rates among participants were similar among those under 12 years (2.8%) and for children 12 years and older (3.0%). Summary data can be found in Table 3.

The majority of secondary cases (68.1%) were identified on the first post exposure testing day, 95.8% by day 4, and 99.6% by day 7 (Fig 1).

In total, we identified 516 possible tertiary cases among 102 373 TTS participants, distributed among 74 schools, representing 0.5% of individuals tested. In the majority of these instances, only 1 or 2 potential tertiary cases were found related to a secondary case identified in TTS. There were 9 instances in which 4 or more cases were identified in the same school and grade in the 2 weeks following a positive secondary case, that may have been due to tertiary transmission.

Implementation feedback from program participants was that staffing challenges and availability of testing supplies were major barriers early, but feasibility and operations improved with experience. Additional feedback that negative results were under-reported due to the staffing burden required to input data led to the development and operationalization of a batch-upload data entry process to improve reporting. Though this reportedly improved reporting, negative results continued to not be reliably entered.

We present findings from the first 13 weeks of a state-wide TTS program. This is the first state-wide, large-scale report in the literature of data and our results are reassuring that a TTS is feasible, safe, and effective, and our findings expand upon the experiences reported from smaller district-level programs with smaller scope.^18,19  Because all schools across the state were given the opportunity to participate, and more than 95% of them opted in, the scale and granular detail available in our study substantially adds to the literature. Over 102 000 individuals had in-school exposure to COVID-19 and participated in the TTS program.

This study was conducted during a period of widespread availability of the COVID-19 vaccine for staff and students aged 12 and up, but also before distribution of vaccine for individuals aged 5 to 11 years, and during a time when the δ variant was the predominant strain. Among participants in this novel state-wide testing program, the per person positivity rate following an in-school exposure was low (2.9%), and similar to in-school contacts testing positive in Massachusetts schools during the Spring of 2020 (2.9%), before the δ variant was widely circulating.²⁰ 

TTS saved a minimum of 325 328 school days during the first 13 weeks of the program with a 54.0% participation rate in the TTS program among students.

The demographics of school districts that opted-in to the state-wide testing program mirrors those from across the state, and only 2 of the 50 largest districts in the state did not participate. The program was also available to students with disabilities and English language learners similar to their representation across the state. There was differential uptake within the schools, such that non White students were less likely to consent to participate than their White counterparts. Equal access to testing is important for achieving educational equity, however outreach efforts may be necessary to ensure equivalent participation.

During the roll-out of this state-wide program, several lessons were learned. The ongoing collaboration between the state and the contracted health care company, and input and support from school nurses were crucial for success to assist with staffing, testing infrastructure, and contact tracing and identification. Early identification and training of staff to collect and process specimens, enter and report test results, and ensure the adequacy of the testing supply chain are critical for a successful implementation. Engagement of key stakeholders with feedback and adaptation is critical to identify local challenges and develop smooth operational processes. Collaboration and consultation with school nurses who have experience running a TTS program in a school setting may help to identify barriers and solutions before the program is implemented. In addition, considerations about staffing requirements and school nursing workload required to conduct contract tracing to identify those eligible to participate in TTS is important for the scale-up and operations of the program.

Our study has several limitations. The number of vaccinated students not eligible for TTS among all students at participating schools is not known; therefore, the actual program participation rate among eligible students is higher than what is reported. Though reporting of all test results was required, several schools indicated positive tests were consistently reported, but that negative results were under-reported due to the staffing burden required to input data, particularly early in the program rollout. Missing negative tests would lead to elevated positivity rates due to an inappropriately low denominator. While statewide guidance is available, individual schools locally interpret and adapt the TTS guidance, resulting in variable implementation of TTS and other infection-control recommendations: schools may define a classroom close contact differently, differentially apply testing recommendations with regard to timing of exposure, or opt to apply a more restrictive definition of classroom close contact than the minimum recommended. This may bias findings in unpredictable ways. Confirmatory testing with PCR was not routinely performed, thus it is possible that some results represent false positives or false negatives. However, a validation study of rapid antigen testing from the Spring of 2020 demonstrated high positive predictive value of the BinaxNow, somewhat mitigating this limitation.¹⁶  We are not able to definitively assess the number of additional transmissions that arose from students who ultimately tested positive but stayed in school due to their participation in the TTS program, but we report a maximum number of tertiary cases based on an extremely sensitive definition. Even with this over-estimate, the number of possible tertiary cases was low (516, 0.5%), and state-wide contact tracing by the Department of Public Health did not identify participation in TTS as the cause of any clusters of COVID-19. In addition, it is reassuring that the majority of positive cases were identified on the first day of post exposure testing and thus, did not spend additional time in the classroom, limiting the potential for onward spread. Additionally, the state Department of Public Health did not identify participation in TTS as the cause of any clusters of COVID-19 cases. Whole genome sequencing of isolates was not performed so it is likely that some of the positive cases identified through the TTS program were not in fact linked to the index case, particularly after community case rates began to rise. Similarly, we are unable to exclude the potential existence of additional exposures that might have occurred out of school, such that actual in-school transmission was likely below the per person test positivity rate in the TTS program. Individuals and those in schools who opted for quarantine rather than participation in TTS may have also tested positive but reporting to the contracted health care companies is not required or closely monitored, so a comparison of secondary cases identified in the TTS program to those who underwent quarantine is not possible. Symptomatic students are sent home and may subsequently have positive COVID-19 tests outside of the program, and thus, may not be reflected in positivity rates, underestimating the true secondary case rate. Because vaccinated individuals were not required to quarantine on exposure and were not routinely tested for COVID-19 under Massachusetts school protocols during the study period, they were not eligible for the TTS program, so we are not able to estimate the rate of breakthrough infections in this population, nor are we able to estimate transmission rate from this population. TTS was offered in the background of robust mitigation measures in place, including a high vaccination rate among adults, and our findings may not be generalizable to a population that does not have this constellation of protections or similarly high vaccination rate. Finally, in the context of a new, more transmissible variant, or one for which available diagnostic tests have different sensitivity or specificity, these findings may no longer be applicable.

During the first 13 weeks of an innovative state-wide TTS program, the per person post exposure test positivity rate was similar to that reported during the spring of 2021 in Massachusetts, with minimal tertiary transmission, even in the setting of the Δ variant. At least 325 328 days of school were saved. 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.

We thank Sorraya Jaiprasert, MPH for her help with data analysis. We also thank the staff of the K–12 schools across the state of Massachusetts for their work throughout the pandemic to keep students in schools and safe.

TTS

Test-To-Stay

DESE

Department of Elementary and Secondary Education