Adsorbed diphtheria-purified pertussis-tetanus combined vaccine(Osaka University)

Objective: To evaluate the epidemiological protective effect of a booster dose of acellular DTP vaccine (DTaP) against pertussis in 6-year-old children. Methods: A retrospective cohort study was conducted to compare the incidence of pertussis in 6-year-old children who received DTaP versus DT vaccine boosters in 2023 over a two-year period from May 2023 to May 2025. The protective effect of the fifth dose of DTaP against pertussis in 6-year-old children was evaluated. Results: A total of 960 participants were enrolled in this study, including 480 children in the experimental group who received the fifth dose of DTaP vaccine and 480 children in the control group who received the DT vaccine booster. Baseline characteristics were balanced between the two groups. There were six confirmed cases of pertussis in the experimental group, with a reported incidence rate of 1.25%. In the control group, 14 pertussis cases were reported, with a reported incidence rate of 2.92%. The protective effectiveness(VE) of the DTaP vaccine against pertussis was 57.14% (95%CI:-10.59%-83.39%). For 6-year-old children who completed the booster immunization, the incidence data of pertussis were collected from the 14^th day after vaccination (i.e., the study day 0). Based on the annual cumulative incidence rate, the VE of DTaP against pertussis at 6, 12, 18, and 24 months after vaccination was 100%, 63.80% (95%CI:-14.49%-88.55%), 64.59% (95%CI: 1.17%-87.31%), and 57.60% (95%CI:-10.80%-83.78%), respectively. In the DTaP group, the annual cumulative incidence rate of 12 to 24 months did not show a significant upward or downward trend (Z=-0.995, P=0.320). Conclusion: Boosting 6-year-old children with the DTaP vaccine provides measurable protection against pertussis. The protective efficacy is significant in the early stage (0 to 6 months) after vaccination, and it still remains effective at 12 to 24 months.

Objective: To analyze the awareness of and factors influencing the adjusted national immunization schedule for the diphtheria-tetanus-acellular pertussis (DTaP) vaccine among grassroots immunization service personnel in China. Methods: Based on the snowball sampling method from January to February 2025, immunization service personnel from all provinces of China were selected from the "Tingting Experts Talk" WeChat platform, with concurrent dissemination through the "National Vaccine-Preventable Diseases Communication Group" WeChat group. The questionnaire included basic demographic characteristics and knowledge of the DTaP vaccine immunization policy (13 questions in total). Respondents who answered ≥10 questions correctly were defined as being aware of the policy adjustment. The multivariable logistic regression analysis was performed to identify factors influencing awareness. Results: A total of 8 030 valid questionnaires were collected from 29 provinces, with a valid response rate of 92.91%. The overall awareness accuracy rates among the Centers for Disease Control and Prevention (CDC) personnel and the point of vaccination (POV) staff were 74.1% and 62.5%, respectively. The awareness rate of the core points of policy adjustment among the research subjects exceeded 90%. Among the questions regarding the operational details of policy implementation, the correct rate of answering questions related to the catch-up vaccination principles was relatively low (37.1%-74.0%). The multivariate logistic regression analysis showed that, compared with those with primary titles, CDC personnel with senior titles had higher mastery of the policy adjustment, with an OR (95%CI) value of 2.238 (1.343-3.730). Compared with those engaged in disease surveillance and immunization strategy research, CDC personnel with other work types had lower awareness of the policy adjustment, with an OR (95%CI) value of 0.404 (0.195-0.833). Compared with those in western regions, with primary titles, and without relevant training, POV staff in central regions, eastern regions, with intermediate titles, with senior titles, with one relevant training session, and with ≥2 relevant training sessions had better awareness of the program adjustment, with OR (95%CI) values of 1.214 (1.085-1.358), 1.412 (1.246-1.600), 1.606 (1.446-1.784), 1.737 (1.443-2.091), 2.254 (1.509-3.366), and 2.674 (1.769-3.981), respectively. Compared with those engaged in information registration/recipient notification, POV staff with vaccination services and other work types had lower awareness of the program adjustment, with OR (95%CI) values of 0.713 (0.633-0.803) and 0.508 (0.427-0.604), respectively. Conclusion: Although grassroots immunization service personnel show an insufficient mastery of certain catch-up vaccination knowledge, they demonstrate a good understanding of overall principles and routine immunization schedules shortly after the policy adjustment, which can effectively ensure an orderly transition between old and new immunization strategies.