COVID-19 Incidence Among Children Not Related to Elementary School Attendance

Among California children eligible for kindergarten, incidence of COVID-19 decreased over time and was generally lower than other published associations between out-of-school child socialization and COVID-19 incidence, according to new research published in the Journal of the American Medical Association.¹

Investigating the true nature of COVID-19 spread in elementary schools are essential for bettering outcomes among children while affording them a proper educational experience. | Image Credit: © LIGHTFIELD STUDIOS | stock.adobe.com

This evidence suggests that, despite schools holding potential for increased disease spread, precautionary measures instituted because of the COVID-19 pandemic were able to successfully mitigate major increases in disease transmission.¹

When the pandemic began, the association of school attendance with the transmission of SARS-CoV-2, the virus that causes COVID-19, was one of the biggest questions among health care professionals as it proved the hardest to answer. Studies investigating transmission among school children related to school were limited early in the pandemic due to concurrent disease mitigation policies, while being costly and cumbersome to conduct.¹

Methods are desperately needed to quantify the association of school attendance with COVID-19 transmission rates. One strategy, employed by the investigators through a regression discontinuity design, is analyzing the age threshold for school eligibility as a variable for school exposures. According to the investigators, this strategy avoids the need for extensive data collection required by cohort studies.¹

In this trial, the investigators utilize regression discontinuity design to estimate the association between school attendance and infectious disease incidence. The investigators assessed this by comparing COVID-19 incidence and hospitalizations among children born after the age threshold for kindergarten eligibility with those born just before. California was chosen as the study setting due to its large public-school enrollment and its status as the most socioeconomically diverse state.¹

The investigators identified a total of 688,278 cases of COVID-19 and 1423 hospitalizations among children who turned 5 years within 224 months of September 1 of the school year when their infection occurred.¹

Data indicates that reported COVID-19 incidence was higher among children eligible for school attendance during in-person semesters in the study period. School eligibility incidence rate ratio (IRR) during the fall 2021 semester was 1.52 (95% CI, 1.36-1.68), indicating that age-adjusted incidence rates were 51.5% higher among children eligible for elementary school than those who were not.¹

IRR for the spring 2022 semester was 1.26 (95% CI, 1.15-1.39) and 1.19 (95% CI, 1.03-1.38) for the fall 2022 semester. Age-adjusted incidence rates were 26.3% and 19.1% higher for the spring 2022 and fall 2022 semesters, respectively. There was a clear jump in transmission in the fall 2021 semester, but the incidence was observed to decline thereafter.¹

Notably, there were no discernible increases in reported age-adjusted COVID-19 hospitalization rates among children born before the school attendance age threshold for any period examined. However, the study authors caution that this observation could be due to the rarity of hospitalization for COVID-19 in children.¹

It is critical to compare these observations to the effects of other common sources of transmission, including child social gatherings and large gatherings among adults. Whaley et al investigated the association between social gatherings and COVID-19 risk utilizing the marker of household birthdays, finding a 31% increase in COVID-19 incidence after birthdays. Notably, this is comparable to the estimated effect sizes for the 3 in-person semesters in this trial.^1,2

Furthermore, Suñer et al conducted a population-based control-matched analysis to discover the association between mass-gathering outdoor events and the incidence of COVID-19. They found that attendees of a large outdoor festival had a higher cumulative COVID-19 incidence post-festival compared with that of control participants. Still, the results from the current trial indicate that the transmission among children in schools was smaller than the transmission associated with large gatherings among adults.³

Some limitations of the trial were acknowledged, including the inability to determine whether higher COVID-19 incidence was due to in-school or out-of-school exposures associated with school attendance, like after school clubs or sports programs. Additionally, the data from the trial may not be generalizable to states aside from California, which had stricter COVID-19 precautionary measures, and for longer than the rest of the country.¹

“The novelty of using this approach to answer questions surrounding infectious disease incidence was both a strength of this study and motivator for future research to characterize sources of bias when using the regression discontinuity approach to study infectious disease transmission within schools,” the investigators concluded.¹

REFERENCES

1. Lin E, Bilinski A, Collender PA, et al. COVID-19 incidence and age eligibility for elementary school. JAMA Netw Open. 2024;7(11):e2444836. doi:10.1001/jamanetworkopen.2024.44836

2. Whaley CM, Cantor J, Pera M, et al. Assessing the association between social gatherings and COVID-19 risk using birthdays. JAMA Intern Med. 2021;181(8):1090-1099. doi:10.1001/jamainternmed.2021.2915

3. Suñer C, Coma E, Ouchi D, et al. Association between two mass-gathering outdoor events and incidence of SARS-CoV-2 infections during the fifth wave of COVID-19 in north-east Spain: A population-based control-matched analysis. The LancetRegional Health – Europe. 2022;15:100337. doi:10.1016/j.lanepe.2022.100337