Objective To investigate public online attention, attitudes, and influencing factors regarding non-national immunization program vaccines (NIPVs) for infants and young children on social media platforms, thereby providing a reference for optimizing vaccine communication strategies.

Methods Daily national Baidu index data for 10 topics related to the pentavalent vaccine, rotavirus vaccine, 13-valent pneumococcal conjugate vaccine (PCV13), and their corresponding diseases from July 2023 to June 2024 were collected. Additionally, 24 353 relevant notes were screened and included from five high-traffic maternal and infant topics—“Baby Vaccines,” “Self-paid Vaccines,” “Pertussis,” “New Moms,” and “Late Pregnancy”—on the Xiaohongshu platform between October 2023 and September 2024. Time-series analysis was conducted to describe trends in public attention. Content analysis was performed to classify attitudes in high-engagement Xiaohongshu notes and to identify the drivers and barriers influencing public vaccination decisions.

Results Baidu index analysis revealed a temporal association between public attention toward NIPVs and the epidemic trends of corresponding diseases. This was most notable during the peak search period for "Pertussis," which coincided with a significant rise in attention for the "Pentavalent vaccine." Content analysis of Xiaohongshu notes indicated that for polyvalent vaccines (represented by the pentavalent vaccine), positive attitudes accounted for 40.88%, driven primarily by the convenience of reduced injection frequency (45.91%). However, negative attitudes were also relatively prominent (12.57%), centering on high costs (16.98%) and the cost-effectiveness of alternative options (18.87%). Public concerns regarding PCV13 and the rotavirus vaccine focused mainly on adverse reactions following immunization, accounting for 20.99% and 21.12%, respectively.

Conclusions Convenience, cost-effectiveness, and safety are the three core dimensions influencing parental decisions regarding NIPV vaccination for infants and young children. Vaccine communication strategies should be tailored to the specific public opinion foci of different vaccine types to break down information barriers and facilitate effective communication within broader maternal and infant communities.