Immunization coverage, knowledge, satisfaction, and associated factors of non-National Immunization Program vaccines among migrant and left-behind families in China: evidence from Zhejiang and Henan provinces.

Background: Migrant and left-behind families are vulnerable in health services utilization, but little is known about their disparities in immunization of non-National Immunization Program (NIP) vaccines. This study aims to evaluate the immunization coverage, knowledge, satisfaction, and associated factors of non-NIP vaccines among local and migrant families in the urban areas and non-left-behind and left-behind families in the rural areas of China.

Methods: A cross-sectional survey was conducted in urban areas of Zhejiang and rural areas of Henan in China. A total of 1648 caregivers of children aged 1-6 years were interviewed face-to-face by a pre-designed online questionnaire, and their families were grouped into four types: local urban, migrant, non-left-behind, and left-behind. Non-NIP vaccines included Hemophilus influenza b (Hib) vaccine, varicella vaccine, rotavirus vaccine, enterovirus 71 vaccine (EV71) and 13-valent pneumonia vaccine (PCV13). Log-binomial regression models were used to calculate prevalence ratios (PRs) and 95% confidence intervals (CIs) for the difference on immunization coverage of children, and knowledge and satisfaction of caregivers among families. The network models were conducted to explore the interplay of immunization coverage, knowledge, and satisfaction. Logistic regression models with odds ratios (ORs) and 95% CIs were used to estimate the associated factors of non-NIP vaccination.

Results: The immunization coverage of all non-NIP vaccines and knowledge of all items of local urban families was the highest, followed by migrant, non-left-behind and left-behind families. Compared with local urban children, the PRs (95% CIs) for getting all vaccinated were 0.65 (0.52-0.81), 0.29 (0.22-0.37) and 0.14 (0.09-0.21) among migrant children, non-left-behind children and left-behind children, respectively. The coverage-knowledge-satisfaction network model showed the core node was the satisfaction of vaccination schedule. Non-NIP vaccination was associated with characteristics of both children and caregivers, including age of children (> 2 years-OR: 1.69, 95% CI: 1.07-2.68 for local urban children; 2.67, 1.39-5.13 for migrant children; 3.09, 1.23-7.76 for non-left-behind children); and below caregivers' characteristics: family role (parents: 0.37, 0.14-0.99 for non-left-behind children), age (≤ 35 years: 7.27, 1.39-37.94 for non-left-behind children), sex (female: 0.49, 0.30-0.81 for local urban children; 0.31, 0.15-0.62 for non-left-behind children), physical health (more than average: 1.58, 1.07-2.35 for local urban children) and non-NIP vaccines knowledge (good: 0.45, 0.30-0.68 for local urban children; 7.54, 2.64-21.50 for left-behind children).

Conclusions: There were immunization disparities in non-NIP vaccines among migrant and left-behind families compared with their local counterparts. Non-NIP vaccination promotion strategies, including education on caregivers, and optimization of the immunization information system, should be delivered particularly among left-behind and migrant families.