Better adherence to childhood Haemophilus influenzae type b vaccination with combination vaccines compared to single-antigen vaccines: Evidence from China

Background The coverage of Haemophilus influenzae type b (Hib) vaccination remains sub-optimal in China, and this study aimed to investigate the influencing factors of caregivers' Hib-containing vaccine choices and the association between combination vaccine use and adherence to Hib immunisation schedule among Chinese children.Methods From August to October 2019, a cross-sectional survey was conducted in 148 community health care centres from ten provinces in China, which collected vaccination records from 5294 children aged 6-59 months. The children were categorised into three groups based on their Hib-containing vaccine receipt: unvaccinated group, monovalent vaccine group, and combination vaccine group. The outcome measures included: (1) receipt and choice of Hib-containing vaccines, and (2) completion of the three-dose schedule. Multinomial logistic regression was used to evaluate the influencing factors of Hib-containing vaccine receipt and choice, and logistic regression was adopted to investigate the associations between vaccine choice and schedule completion.Results Of the 5294 children, 19.53% received monovalent vaccines only, 22.59% received at least one dose of combination vaccines, and 57.88% were not vaccinated against Hib. The overall three-dose completion rate was 27.03%. The multinomial logistic (mlogit) regression findings indicated strong associations of socioeconomic status and Hib-containing vaccine supply with vaccination status. Multiple logistic regression among those who received at least one Hib-containing dose demonstrated a 3-fold increase in the likelihood of three-dose schedule completion by children who received any combination dose compared with those received single-antigen vaccines only (adjusted odds ratio (aOR) = 3.97 (95% CI = 3.14-5.03)). Conclusions Findings from the current study provide a more comprehensive understanding of the strong relationship between combination vaccine receipt and completion outcomes. Facing the suboptimal Hib vaccination rate in China, the use of combination vaccines could help increase vaccination compliance, and appropriate government actions to reduce out-of-pocket burden of immunisation are encouraged to address inequities in vaccine choices.