Int J Infect Dis. 2026 Apr 2:108672. doi: 10.1016/j.ijid.2026.108672. Online ahead of print.
ABSTRACT
OBJECTIVES: To compare secondary SARS-CoV-2 transmission detected through RT-PCR screening in childcare and school-aged settings during the Omicron wave.
METHODS: We analyzed Okinawa School PCR Project events from January 1 to March 11, 2022, in which secondary cases were ascertained through school-based RT-PCR screening conducted after the last exposure. Index cases were classified as child/student or teacher/staff. Secondary cases were defined as RT-PCR-confirmed infections detected through school-based screening. We estimated the proportion of events with ≥1 secondary case and the mean number of secondary cases per event (Revent).
RESULTS: Among 897 events with known index case role, 73.1% detected no secondary cases. In nurseries/kindergartens, secondary cases were detected in 32.3% of teacher/staff-index events (Revent 0.62; 95% CI 0.53-0.72), compared with 12.8% in elementary and secondary schools (Revent 0.15; 95% CI 0.06-0.33). No secondary infections were detected after teacher/staff-index events in junior high (n=11) or high schools (n=6).
CONCLUSIONS: Childcare worker-index events in nurseries and kindergartens generated secondary cases in ≈30% of events, whereas teacher/staff-index events in elementary and secondary schools infrequently generated secondary cases under mitigation measures. Prioritizing screening and prevention resources toward childcare workers may improve efficiency when diagnostic capacity is constrained.
PMID:41935615 | DOI:10.1016/j.ijid.2026.108672
