Notes From the Field: School-Based and Laboratory-Based Reporting of Positive COVID-19 Test Results Among School-Aged Children — New York, September 11, 2021–April 29, 2022

By April 29, 2022, a total of 702,686 COVID-19 cases were reported among children and adolescents aged 5–17 years in the state of New York.* Pediatric COVID-19 cases and hospitalizations increased during the 2021–22 school year, driven by transmission of the Omicron variant^† (1). In late 2021, during the surge in Omicron BA.1 variant cases, state^§ and federal^¶ authorities expanded access to self-administered, at-home rapid antigen tests, which can increase a person’s knowledge of their COVID-19 status and guide risk-reduction behaviors. New York government agencies sent millions of these tests to schools for distribution to teachers, students, and staff members. Because results of self-administered, at-home tests are not captured by electronic laboratory reporting (in contrast to health care provider–administered tests at a physician’s office or laboratory that are reported through electronic health records or other means), expanded use of these tests might affect interpretation of trends in reported COVID-19 cases; however, this has yet to be assessed** (2). Furthermore, understanding changes in testing behavior before and after the Omicron variant surge might help public health officials better use available COVID-19 data to guide future policy.

COVID-19 case data from two independently operating New York State Department of Health systems were compared before and after expansion of at-home testing: 1) laboratory-reported data^†† for children and adolescents aged 5–17 years and 2) a kindergarten through grade 12 (K–12) school-based system^§§ for reporting positive results from all testing sources^¶¶ (3). Laboratory-reported data include results of school-administered tests (which are required to be reported) but exclude results from self-administered, at-home tests. School-reported data include positive results reported to the state from any test source, including those from clinical settings, school-based testing programs, and self-administered, at-home tests. Case totals for both data sets*** and the ratio of school-reported to laboratory-reported cases were calculated weekly during September 11, 2021–April 29, 2022, and compared. This activity was reviewed by CDC and was conducted consistent with applicable federal law and CDC policy.^†††

During the September 11–17, 2021, school week, among 6,928 New York schools, 5,201 (75.1%) reported to the school-based system; by the April 23–29, 2022, school week, 5,274 (76.1%) schools reported (weekly median = 80.7%; IQR = 76.1%–81.7%). During the entire analysis period, 477,538 student cases were reported to the K–12 school-based system, and 464,421 cases in children and adolescents aged 5–17 years were reported by laboratories^§§§; the overall ratio of school-reported to laboratory-reported cases was 1.03. During September 11–December 31, 2021, the ratio of school-reported to laboratory-reported cases was stable and near 1.0 (median = 0.82; IQR = 0.73–0.85) (Figure). From the January 1–7 to the April 29, 2022, school week, during and following state and federal expansion of at-home testing, the ratio of school-reported to laboratory-reported cases increased 167%, from 1.36 to 3.64 (median = 1.58; IQR = 1.36–2.13).

These findings are subject to at least three limitations. First, because school-reported data include some students aged <5 years or >17 years, and not all children and adolescents aged 5–17 years attend schools that reported cases, school-reported and laboratory-reported case data were not directly comparable. Second, these results might reflect both underreporting of infection and increased detection because of at-home test use. Finally, results from school-aged children and adolescents are not representative of those from the general population.

The changing relationship between school-reported and laboratory-reported data, during a period of stable school reporting, suggests a decline in the capture of positive laboratory test result data for children and adolescents aged 5–17 years following the expansion of at-home testing. Throughout the pandemic, public health programs have relied on laboratory-reported data to guide risk communication; underestimation of cases based on these data could affect interpretations of epidemic trends and metrics derived from them, including community COVID-19 incidence. This analysis suggests that methods of capturing data on results from self-administered, at-home tests can augment laboratory-reported data to provide a more complete picture of positive COVID-19 test results within communities. Jurisdictions that prioritize both at-home COVID-19 testing and comprehensive epidemiologic monitoring of the COVID-19 pandemic might consider implementing reporting systems that operate alongside electronic laboratory reporting. As the pandemic has evolved, however, the level of vaccine- and infection-derived immunity has increased in the population; thus, prioritization of reducing medically significant illness and minimizing strain on the health care system has increased.^¶¶¶ Health officials and the public should consider current information about COVID-19 cases and hospitalizations in the community, as well as the potential for strain on the local health system, when making decisions about community prevention strategies and individual behaviors.****

Corresponding author: Travis T. O’Donnell, travis.odonnell@health.ny.gov.

¹New York State Department of Health; ²School of Public Health, University at Albany, State University of New York, Rensselaer, New York; ³Division of Viral Diseases, National Center for Immunization and Respiratory Diseases, CDC.

References

1. Shi DS, Whitaker M, Marks KJ, et al.; COVID-NET Surveillance Team. Hospitalizations of children aged 5–11 years with laboratory-confirmed COVID-19—COVID-NET, 14 states, March 2020–February 2022. MMWR Morb Mortal Wkly Rep 2022;71:574–81. https://doi.org/10.15585/mmwr.mm7116e1 PMID:35446827
2. Rader B, Gertz A, Iuliano AD, et al. Use of at-home COVID-19 tests—United States, August 23, 2021–March 12, 2022. MMWR Morb Mortal Wkly Rep 2022;71:489–94. https://doi.org/10.15585/mmwr.mm7113e1 PMID:35358168
3. Rosenberg ES, Dufort EM, Blog DS, et al.; New York State Coronavirus 2019 Response Team. COVID-19 testing, epidemic features, hospital outcomes, and household prevalence, New York State—March 2020. Clin Infect Dis 2020;71:1953–9. https://doi.org/10.1093/cid/ciaa549 PMID:32382743

FIGURE. School-reported* and laboratory-reported^† COVID-19 cases — New York, September 11, 2021–April 29, 2022

* School-reported data include positive results from any test source, reported through the New York state COVID-19 report card system for children in kindergarten through grade 12.

^† Laboratory-reported data include positive results of SARS-CoV-2 reverse transcription–polymerase chain reaction and antigen tests conducted at laboratories or physician offices, reported through electronic health records or other means.