Parental decisions regarding the vaccination of children and adolescents against SARS-CoV-2 from 2020 to 2023: A descriptive longitudinal study of parents and children in Montreal, Canada

Background

Given the growing evidence on the benefits of hybrid immunity, continued monitoring of vaccine uptake is warranted, particularly of socio-demographic subgroups with early vaccine hesitancy. Racial/ethnic and lower income groups experienced a high infection incidence, but few studies account for the child's history of SARS-CoV-2 infection on the parent's decision to vaccinate their child.

Methods

EnCORE is a SARS-CoV-2 pediatric cohort study comprising five rounds of data collection from 2020 to 2023, with parental questionnaires at each round. Parent's responses on their intention to vaccinate their child and their reasons were summarized descriptively. Vaccine uptake was estimated through time and in relation to participant characteristics, using multivariable regression to adjust for covariates including a history of PCR/serology-confirmed SARS-CoV-2 infection prior to vaccine eligibility. At study end, we estimated the average time lapsed from last vaccine dose.

Results

The samples for vaccine uptake and intention to vaccinate analyses were 631 and 1137 participants, respectively. At study end, uptake was 88 % but approximately 49 % of 2-to-4-year-olds remained unvaccinated (95 % CI 39.0, 58.1) and for vaccinated participants the median time since last vaccination was 353 days. In regression analyses, after adjusting for infection prior to vaccine eligibility and other covariates, we found approximately a two-fold increase in unvaccinated status associated with the parent's identification as a racial/ethnic minority and with household income in the lowest sample tercile (minority: adjusted relative risk [aRR] 2.45, 95 % CI 1.56, 3.86; income: aRR 1.76, 95 % CI 1.17, 2.66).

Conclusion

By mid-2023, most participants were not protected by vaccine-induced antibodies, because they were unvaccinated or several months had lapsed from their last dose. A COVID-19 infection prior to vaccine eligibility was associated with a greater risk of remaining unvaccinated but did not fully account for low uptake in ethnic/racial minorities and lower income groups.