Timing of outbreak-triggered unit-wide screening and COVID-19 outbreak size in long-term care and related social welfare facilities in Okinawa, Japan
9 affiliations
- 1Graduate School of Advanced Integrated Studies in Human Survivability, Kyoto University, Kyoto, Kyoto, Japan
- 2Emergency Medical Center, Urasoe General Hospital, Urasoe, Okinawa, Japan
- 3The Okinawa Prefecture Commission for Epidemiological and Statistical Analysis, Naha, Okinawa, Japan
- 4Unité d’Epidémiologie des Maladies Emergentes, Institut Pasteur, Université Paris Cité, Paris, France
- 5Pasteur International Unit at Kumamoto University/Japan Institute for Health Security, Tokyo, Japan
- 6Joint Research Center for Human Retrovirus Infection, Kumamoto University, Kumamoto, Japan
- 7Department of Emergency Medicine, Nakagami Hospital, Okinawa, Okinawa, Japan
- 8Okinawa Prefectural Government, Naha, Okinawa, Japan
- 9Division of Infectious Diseases, Okinawa Prefectural Chubu Hospital, Uruma, Okinawa, Japan
Abstract
Objectives: Coronavirus disease 2019 outbreaks in long-term care facilities can spread rapidly, but evidence on whether delayed outbreak-triggered unit-wide screening is associated with outbreak size is limited.
Methods: We conducted a retrospective observational study using outbreak-support records from long-term care and related social welfare facilities in Okinawa Prefecture, Japan, from April to September 2022. We included outbreaks with documented unit-wide screening. The outcome was the final outbreak size. The exposure was the delay from outbreak recognition to the first unit-wide screening (same day, 1 day, 2 days, or ≥3 days). We used multivariable negative binomial regression, adjusting for index case type, facility type, recognition period, and facility-level resident vaccination coverage.
Results: We analyzed 707 outbreaks. Compared with same-day screening, the adjusted incidence rate ratios for outbreak size were 0.95 (95% confidence interval 0.72-1.26) for a 1-day delay, 1.16 (0.87-1.54) for a 2-day delay, and 1.44 (1.09-1.91) for delays of ≥3 days. The association was attenuated after adjustment for on-site infection prevention and control visit timing.
Conclusion: Delays of ≥3 days from outbreak recognition to the first unit-wide screening were associated with a larger final outbreak size. Earlier outbreak-triggered screening may support outbreak control in long-term care facilities, although causal interpretation is limited by the observational design.
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BibTeX
@article{xu2026timing,
title = {{Timing of outbreak-triggered unit-wide screening and COVID-19 outbreak size in long-term care and related social welfare facilities in Okinawa, Japan}},
author = {Yining S. Xu and Kuniko Takahashi and Yusuke Shimakawa and Takashi Nakamura and Toru Itokazu and Yoshihiro Takayama and Kenji Mizumoto},
journal = {IJID Regions},
year = {2026},
month = oct,
doi = {10.1016/j.ijregi.2026.101042},
url = {https://doi.org/10.1016/j.ijregi.2026.101042},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Timing of outbreak-triggered unit-wide screening and COVID-19 outbreak size in long-term care and related social welfare facilities in Okinawa, Japan
AU - Yining S. Xu
AU - Kuniko Takahashi
AU - Yusuke Shimakawa
AU - Takashi Nakamura
AU - Toru Itokazu
AU - Yoshihiro Takayama
AU - Kenji Mizumoto
PY - 2026
DA - 2026/10/13
JO - IJID Regions
DO - 10.1016/j.ijregi.2026.101042
UR - https://doi.org/10.1016/j.ijregi.2026.101042
AB - Objectives: Coronavirus disease 2019 outbreaks in long-term care facilities can spread rapidly, but evidence on whether delayed outbreak-triggered unit-wide screening is associated with outbreak size is limited. Methods: We conducted a retrospective observational study using outbreak-support records from long-term care and related social welfare facilities in Okinawa Prefecture, Japan, from April to September 2022. We included outbreaks with documented unit-wide screening. The outcome was the final outbreak size. The exposure was the delay from outbreak recognition to the first unit-wide screening (same day, 1 day, 2 days, or ≥3 days). We used multivariable negative binomial regression, adjusting for index case type, facility type, recognition period, and facility-level resident vaccination coverage. Results: We analyzed 707 outbreaks. Compared with same-day screening, the adjusted incidence rate ratios for outbreak size were 0.95 (95% confidence interval 0.72-1.26) for a 1-day delay, 1.16 (0.87-1.54) for a 2-day delay, and 1.44 (1.09-1.91) for delays of ≥3 days. The association was attenuated after adjustment for on-site infection prevention and control visit timing. Conclusion: Delays of ≥3 days from outbreak recognition to the first unit-wide screening were associated with a larger final outbreak size. Earlier outbreak-triggered screening may support outbreak control in long-term care facilities, although causal interpretation is limited by the observational design.
SN - 2772-7076
ER -