Understanding paediatric COVID-19 vaccination during the pandemic: a prospective cohort and a population-based registry study

Yanyan Ni; Francis P Flores; Phyllis Lun; Ke Ning; Mathew S C Chow; Linwei Tian; Sheng-Hsuan Lin; Hugh S Lam; Benjamin J Cowling; David M Bishai; Gabriel M Leung; Michael Y Ni

doi:10.1016/j.lanwpc.2023.100976

Understanding paediatric COVID-19 vaccination during the pandemic: a prospective cohort and a population-based registry study

Lancet Reg Health West Pac. 2023 Nov 23:43:100976. doi: 10.1016/j.lanwpc.2023.100976. eCollection 2024 Feb.

Authors

Yanyan Ni¹, Francis P Flores¹, Phyllis Lun¹, Ke Ning¹, Mathew S C Chow¹, Linwei Tian¹, Sheng-Hsuan Lin², Hugh S Lam³, Benjamin J Cowling^{1

4

5}, David M Bishai¹, Gabriel M Leung^{1

4

5}, Michael Y Ni^{1

6

7}

Affiliations

¹ School of Public Health, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China.
² Institute of Statistics, National Yang Ming Chiao Tung University, Taiwan.
³ Department of Paediatrics, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong Special Administrative Region, China.
⁴ World Health Organization Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, The University of Hong Kong, Hong Kong Special Administrative Region, China.
⁵ Laboratory of Data Discovery for Health (D24H), Hong Kong Science and Technology Park, Hong Kong Special Administrative Region, China.
⁶ State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong Special Administrative Region, China.
⁷ Urban Systems Institute, The University of Hong Kong, Hong Kong Special Administrative Region, China.

Abstract

Background: Despite the early demonstrated safety and effectiveness of COVID-19 vaccines in children, uptake was slow throughout the pandemic and remains low globally. Understanding vaccine refusal could provide insights to improving vaccine uptake in future pandemics.

Methods: In a population-wide registry of all COVID-19 paediatric vaccination appointments, we used interrupted time series analysis to evaluate the impact of public policies. In a population-based cohort of adults, we used population attributable fractions to assess the individual and joint contributions of potential determinants to paediatric COVID-19 vaccination, and used mediation analysis to identify modifiable mediators between political views and paediatric vaccination.

Findings: School vaccination requirements were associated with an increase in vaccination appointments by 278.7% (95% CI 85.3-673.9) in adolescents aged 12-17 and 112.8% (27.6-255.0) in children aged 5-11. Government-mandated vaccine pass, required for entry into restaurants, shopping malls and supermarkets, was associated with increased vaccination appointments by 108.7% (26.6-244.0) in adolescents. The following four determinants may explain 82.5% (63.5-100.0) of the reasons why children were unvaccinated: familial political views, vaccine hesitancy for children, mistrust in doctors and academics, and vaccine misconceptions. The influence of political views may be mitigated since 95.9% (76.4-100.0) of its association with vaccine reluctance for adolescents was mediated by modifiable factors such as mistrust in health authorities and low vaccine confidence.

Interpretation: School vaccination requirements and vaccine passes were associated with increased vaccine uptake. Clinicians should recognise that factors beyond health, such as political views, can influence paediatric vaccine uptake to a significant extent. Nonetheless, such influences could be mitigated by targeted interventions and public policies.

Funding: Hong Kong Jockey Club Charities Trust, Research Grants Council, University Grants Committee, and Health Bureau.

Keywords: COVID-19 vaccine; Children; Epidemiology; Longitudinal; Registry; School vaccination policy; Vaccine pass; Vaccine refusal.