Charland Katia, Quach Caroline, Papenburg Jesse, Pierce Laura, Tuong Nguyen Cat, Saucier Adrien, Barbosa Da Torre Margot, Hamelin Marie-Ève, Carbonneau Julie, Boivin Guy, Zinszer Kate
Centre for Public Health Research, University of Montreal, Montreal, Quebec, Canada.
Departments of Microbiology, Infectious Diseases & Immunology and of Pediatrics, University of Montreal, Montreal, Quebec, Canada.
Vaccine. 2025 Jan 1;43(Pt 1):126489. doi: 10.1016/j.vaccine.2024.126489. Epub 2024 Nov 2.
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.
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.
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).
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.
鉴于越来越多的证据表明混合免疫有益，持续监测疫苗接种情况是有必要的，尤其是对那些早期对疫苗存在犹豫的社会人口亚组。种族/族裔群体和低收入群体感染率较高，但很少有研究考虑儿童的新冠病毒感染史对其父母为孩子接种疫苗决策的影响。
EnCORE是一项新冠病毒儿科队列研究，包括从2020年到2023年的五轮数据收集，每轮都有家长问卷。对家长关于为孩子接种疫苗的意愿及原因的回答进行描述性总结。通过时间以及与参与者特征的关系来估计疫苗接种率，使用多变量回归来调整协变量，包括在符合疫苗接种条件之前经PCR/血清学确认的新冠病毒感染史。在研究结束时，我们估计了距最后一剂疫苗的平均时间间隔。
疫苗接种率和接种意愿分析的样本分别为631名和1137名参与者。在研究结束时，接种率为88%，但约49%的2至4岁儿童仍未接种疫苗（95%可信区间39.0，58.1），对于已接种疫苗的参与者，自上次接种以来的中位时间为353天。在回归分析中，在调整了符合疫苗接种条件之前的感染情况和其他协变量后，我们发现，父母被认定为种族/族裔少数群体以及家庭收入处于样本最低三分位数与未接种疫苗状态增加约两倍相关（少数群体：调整后相对风险[aRR]2.45，95%可信区间1.56，3.86；收入：aRR 1.76，95%可信区间1.17，2.66）。
到2023年年中，大多数参与者未受到疫苗诱导抗体的保护，因为他们未接种疫苗或距最后一剂疫苗已过去数月。在符合疫苗接种条件之前的新冠病毒感染与仍未接种疫苗的更大风险相关，但不能完全解释种族/族裔少数群体和低收入群体的低接种率。
