Immunogenicity and safety of concomitant administration of the sabin-strain-based inactivated poliovirus vaccine, the diphtheria-tetanus-acellular pertussis vaccine, and measles-mumps-rubella vaccine to healthy infants aged 18 months in China

[[[ Objectives: ]]] During the COVID-19 pandemic, there was a decline in vaccine coverage, and the implementation of combined vaccines and co-administration strategies emerged as potential solutions to alleviate this predicament. Our objective is to delve into the concurrent administration of the sabin-strain-based inactivated poliovirus vaccine (sIPV), the diphtheria-tetanus-acellular pertussis vaccine (DTaP), and measles-mumps-rubella vaccine (MMR), with the intention of bridging the evidentiary gap pertaining to vaccine co-administration in Chinese infants, and to ensure a safe and effective vaccination strategy, ultimately leading to an augmentation in immunization coverage. [[[ Methods: ]]] This study was a follow-up trial of the “Immunogenicity and safety of concomitant administration of the sIPV with the DTaP vaccine in children: a multicenter, randomized, non-inferiority, controlled trial.” Blood samples were collected on day 0 and day 30, and serum antibody levels were detected to measure antibody responses to each of the antigens. Local and systemic adverse events were monitored and compared among groups. This study is the first to fill the knowledge gap in China regarding the safe and effective combined vaccination of sIPV, DTaP, and MMR vaccines. [[[ Results: ]]] The geometric mean titer of the poliovirus types I, II, and III neutralizing antibodies were 1060.22 (95% CI: 865.73-1298.39), 1537.06 (95% CI: 1324.27-1784.05), and 1539.10 (95% CI: 1296.37-1827.29) in group I on day 30; geometric mean titer of antibodies against DTaP and MMR in the simultaneous vaccination group was non-inferior to those in the DTaP alone and MMR alone group. Reporting rates of local and systemic adverse reactions were similar between groups and no serious adverse events were reported throughout the clinical study period. [[[ Conclusion: ]]] Co-administration of the sIPV, DTaP, and MMR was safe and did not impact immunogenicity, which would help to mitigate administrative costs and enhance vaccine coverage rates.