SARS-CoV-2 infection characteristics among students and staff in a large high school COVID-19 outbreak and secondary transmission in households

Chen Stein-Zamir; Ora Sinai-Zaken; Eti Zvulun; Ghada Najajra; Rinat Pinto; Shahar Koren; Hanna Shoob; Nitza Abramson

doi:10.1016/j.imj.2023.02.003

SARS-CoV-2 infection characteristics among students and staff in a large high school COVID-19 outbreak and secondary transmission in households

Infect Med (Beijing). 2023 Mar;2(1):36-43. doi: 10.1016/j.imj.2023.02.003. Epub 2023 Mar 2.

Authors

Chen Stein-Zamir^{1

2}, Ora Sinai-Zaken¹, Eti Zvulun¹, Ghada Najajra¹, Rinat Pinto¹, Shahar Koren^{1

2}, Hanna Shoob¹, Nitza Abramson¹

Affiliations

¹ Jerusalem District Health Office, Ministry of Health, Jerusalem, Israel.
² Faculty of Medicine, The Hebrew University of Jerusalem, The Hebrew University and Hadassah Braun School of Public Health and Community Medicine, Jerusalem, Israel.

Abstract

Background: SARS-CoV-2 clinical presentation is associated with the patients' age group. Overall, young individuals present higher proportions of asymptomatic or mild COVID-19 infection, compared to adults. Data on secondary COVID-19 transmission in households, according to the cases' age group, are accumulating.

Methods: We performed a follow-up cohort study including all COVID-19 real-time polymerase chain reaction (RT-PCR)-confirmed cases (adolescent students and school staff) diagnosed in an epidemiological investigation of a large high school outbreak. We compared the adolescent and adult groups regarding clinical symptoms, time to negative COVID-19 RT-PCR tests, and infection transmission in households.

Results: The study population included 817 persons. The confirmed COVID-19 RT-PCR outbreak cases (n = 178) were followed (students aged 12-19 years, median age 14 years, n = 153, school staff aged 24-67 years, median age 39 years, n = 25) and the cases' household close contacts (n = 639) were tested. The adolescents had lower symptomatic infection rates, shorter time to negative COVID-19 RT-PCR tests, and lower transmission rates to household members, compared to the adults. The general transmission rate among household contacts was 13.5%, (86/639) ranging from 8.6% in asymptomatic students' contacts to 27.3% in symptomatic staff contacts. COVID-19 transmission rates were significantly higher in contacts of symptomatic cases compared to asymptomatic cases (odds ratio: 2.06, 95% CI 1.26-3.4) and higher in adults compared to adolescents (odds ratio: 2.69, 95% CI 1.43-4.89).

Conclusions: Adolescents and adults diagnosed in an outbreak investigation differ as to COVID-19 clinical presentation and transmission. As adolescents may show mild or no symptoms, COVID-19 prevention in school settings is challenging. Implementing nonpharmaceutical measures and promoting vaccination programs in eligible staff and students should be considered.

Keywords: Adolescents; COVID-19; Epidemiology; Household; School; Transmission.