619 - Impact of the COVID-19 Omicron Variant Outbreak at Nursery Schools in Minato-City, Tokyo, Japan
Saturday, April 29, 2023
3:30 PM – 6:00 PM ET
Poster Number: 619 Publication Number: 619.225
Haruka Numata, Aiiku Hospital, Minato-ku, Tokyo, Japan; Takashi Urashima, Aiiku Hospital, Minato, Tokyo, Japan; Yusuke Nakamura, Aiiku Hospital, Minato-ku, Tokyo, Japan; Satoru Ishikawa, Aiiku Hospital, Minato, Tokyo, Japan; Chisato Umeda, Jikei University School of Medicine, Minato-City, Tokyo, Japan; Mayu Tahara, The Jikei Medical University School of Medicine, Tokyo, Tokyo, Japan
Background: The number of children with the COVID-19 Omicron variant has increased dramatically since the outbreak of it, resulting in a series of closures of nursery schools and becoming a social problem. Objective: In order to examine Whether it could be effective to close nursery schools in reducing virus transmission, we investigated the transmission of infection in nursery schools before and after the Omicron variant outbreak. Design/Methods: In the period before the Omicron epidemic, 68 nursery schools in Minato City were targeted from July 2020 to August 2021, and PCR test was performed on contacts of children with COVID-19 (children with the consent of their parents). During the Omicron epidemic, PCR test was performed at 15 nursery schools in Minato City from January 9 to January 20, 2022. All children in the same class who could not wear masks were considered as contacts, and we asked them to refrain from attending nursery schools for 6 days from the date the index case last attended school. Results: In the period before the Omicron epidemic, 19 (4.12%) of 461 contacts were PCR-positive. During the Omicron epidemic, 11 (6.4%) of 171 contacts were PCR-positive, and only 2 of the 11 nursery schools had asymptomatic positive cases when there were no positive cases or symptomatic cases other than the index case. We found that there were asymptomatic positive cases in almost all cases there were two or more positive or symptomatic cases in a same nursery school. The number of cases that occurred covid-19 while refraining from attending nursery schools ranged from 15 to 30%.
Conclusion(s): Because Omicron variant became pandemic, the number of childlen with COVID-19 in nursery schools increased. We supposed that it could be effective to close nursery schools and isolate in reducing virus transmission only when there were two or more positive or symptomatic cases in a same class at a nursery school and it would prevent their parents from unnecessarily taking time off work and also would be easy to do social activities for their parents.
