Within-household SARS-CoV-2 transmission and vaccine effectiveness in the first three COVID-19 school outbreaks in northern Viet Nam, September–December 2021

Authors

  • Trang Thu Vu National Centre for Epidemiology and Population Health, College of Health and Medicine, Australian National University, Canberra, Australian Capital Territory, Australia; Department of Communicable Disease Control and Prevention, National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam https://orcid.org/0000-0001-7486-8900
  • Tu Huy Ngo Department of Communicable Disease Control and Prevention, National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam; Field Epidemiology Training Program, National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam
  • Khanh Cong Nguyen Department of Communicable Disease Control and Prevention, National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam; Field Epidemiology Training Program, National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam
  • Vu Thi Lan Ha Nam Center for Disease Control, Ha Nam, Viet Nam
  • Cu Thi Bich Hanh Phu Tho Center for Disease Control, Phu Tho, Viet Nam
  • Le Hong Son Thanh Hoa Center for Disease Control, Thanh Hoa, Viet Nam
  • Huyen Thi Nguyen National Centre for Epidemiology and Population Health, College of Health and Medicine, Australian National University, Canberra, Australian Capital Territory, Australia; Department of Communicable Disease Control and Prevention, National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam
  • Hien Thi Nguyen National Centre for Epidemiology and Population Health, College of Health and Medicine, Australian National University, Canberra, Australian Capital Territory, Australia; Department of Communicable Disease Control and Prevention, National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam
  • Nghia Duy Ngu Department of Communicable Disease Control and Prevention, National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam
  • Duong Nhu Tran National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam
  • Duc-Anh Dang National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam
  • Florian Vogt National Centre for Epidemiology and Population Health, College of Health and Medicine, Australian National University, Canberra, Australian Capital Territory, Australia; The Kirby Institute, University of New South Wales, Sydney, New South Wales, Australia
  • Thai Quang Pham Department of Communicable Disease Control and Prevention, National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam; Department of Research Methodology and Biostatistics, School of Preventive Medicine and Public Health, Hanoi Medical University, Hanoi, Viet Nam

DOI:

https://doi.org/10.5365/wpsar.2024.15.3.1077

Keywords:

SARS-CoV-2, infection transmission, children, school, households, vaccine effectiveness

Abstract

Objective: The risk of transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from schoolchildren to their household and the protective effects of vaccination in these settings remain poorly understood. We assessed the transmission dynamics of schoolchildren with SARS-CoV-2 within their households and the protective effects of coronavirus disease (COVID-19) vaccination among household members in Viet Nam.

Methods: We estimated the attack rate, vaccine effectiveness and adjusted risk ratio (aRR) of factors associated with SARS-CoV-2 transmission to household contacts of children confirmed to have COVID-19 who attended three schools in Ha Nam, Phu Tho and Thanh Hoa provinces between September and December 2021 using multivariable regression with household-level random effects.

Results: This retrospective cohort study included 157 children infected with SARS-CoV-2 and their 540 household contacts. The attack rate among household contacts was 24.6% (133/540). Overall, vaccine effectiveness among household contacts was 39% (95% confidence interval [CI]: -1 to -63), higher among males than females and higher in adults aged >40 years. COVID-19 transmission was greater among female household contacts compared with males (aRR: 1.35, 95% CI: 0.94 to 1.95), although not statistically significant, and highest among those aged 19–39 years (aRR: 2.51, 95% CI: 1.50 to 4.21). Fully vaccinated household contacts had significantly lower infection risk (aRR: 0.46, 95% CI: 0.26 to 0.84).

Discussion: We found substantial onward transmission of SARS-CoV-2 from schoolchildren to household members, and older people were more likely to be protected by vaccination. We recommend that schoolchildren and all household members living with schoolchildren receive at least two doses of a COVID-19 vaccine. Recognizing the role of schoolchildren in the onward transmission of COVID-19 is an important lesson learned by Viet Nam that can help not only in managing other outbreaks but also in protecting schoolchildren by predicting the progress of the outbreak and preparing for a timely response.

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Published

11-07-2024

How to Cite

1.
Vu TT, Ngo TH, Nguyen KC, Lan VT, Bich Hanh CT, Son LH, Nguyen HT, Nguyen HT, Ngu ND, Tran DN, Dang D-A, Vogt F, Pham TQ. Within-household SARS-CoV-2 transmission and vaccine effectiveness in the first three COVID-19 school outbreaks in northern Viet Nam, September–December 2021. Western Pac Surveill Response J [Internet]. 2024 Jul. 11 [cited 2026 Apr. 8];15(3). Available from: https://ojs.wpro.who.int/ojs/index.php/wpsar/article/view/1077

Issue

Vol. 15 No. 3 (2024): July ‒ September

Section

Original Research

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