Top 5 Takeaways

1. Test to Stay (TTS) Implementation: 90 schools in Lake County, Illinois, implemented the TTS strategy during fall 2021, allowing close contacts with masked COVID-19 exposures to remain in school.
2. Secondary Transmission Rate: The secondary transmission rate among TTS participants was 1.5%, with no tertiary transmission observed among school-based contacts.
3. In-Person Learning Days Preserved: The TTS strategy preserved up to 8,152 in-person learning days by allowing students to stay in school instead of quarantining at home.
4. Household Tertiary Cases: Nine tertiary cases were identified among household contacts of the 16 secondary cases, with four of the nine being fully vaccinated.
5. Public Health Implications: TTS, combined with other prevention strategies like masking and physical distancing, can help maintain low transmission rates in schools and sustain in-person learning.

Original Article Author and Citation

Corresponding Author

Emily J. Holman, ryj9@cdc.gov

Suggested Citation

Nemoto N, Dhillon S, Fink S, et al. 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. MMWR Morb Mortal Wkly Rep 2021;70:1778–1781. DOI: http://dx.doi.org/10.15585/mmwr.mm705152e2

Summary

During fall 2021, 90 schools in Lake County, Illinois, implemented the Test to Stay (TTS) strategy, allowing close contacts with masked COVID-19 exposures to remain in school. The secondary transmission rate among TTS participants was 1.5%, with no tertiary transmission observed among school-based contacts. However, nine tertiary cases were identified among household contacts. The TTS strategy preserved up to 8,152 in-person learning days, highlighting its potential to maintain low transmission rates and sustain in-person learning.

Methods

The study involved 90 schools in Lake County, Illinois, which implemented the TTS strategy from August 9 to October 29, 2021. Eligibility for TTS required masked exposure, asymptomatic status, consistent mask-wearing, physical distancing, and SARS-CoV-2 testing on days 1, 3, 5, and 7 post-exposure. Data on COVID-19 cases and close contacts were reported to the Lake County Health Department (LCHD) and analyzed using SAS software.

Discussion

The implementation of TTS, combined with other prevention strategies such as masking and physical distancing, resulted in low secondary transmission rates in schools. The strategy preserved significant in-person learning days and demonstrated the importance of maintaining multiple concurrent prevention strategies. However, the study noted challenges in implementation, particularly for low-resource schools, and highlighted the need for equitable access to staffing and testing supplies.

Conclusion

The TTS strategy effectively limited in-school transmission of SARS-CoV-2 and preserved in-person learning days. While vaccination remains the primary recommendation for COVID-19 prevention, TTS offers an alternative for allowing close contacts to remain in the classroom. Ensuring equitable access to resources is crucial for the successful implementation of TTS in all school settings.

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