The inactivated quadrivalent influenza vaccine (IIV4) and the 23-valent pneumococcal polysaccharide vaccine (PPSV23) have been administered for years and could be administered concomitantly if necessary. However, the immunogenicity and safety of the concomitant administration of these two vaccines have not been well documented, especially in the Chinese population. In this study, 480 participants aged 60 years and older were randomly assigned to the concomitant administration group (C group) or the separate administration group (S group) to receive IIV4 and PPSV23 either concomitantly or separately. Blood samples were collected before and 28 days after each vaccination. The antibodies against four influenza virus strains and twenty-three pneumococcus serotypes were tested. The results showed that the geometric mean titer (GMT) ratios (C group to S group) for the four influenza strains ranged from 0.72 to 0.95, with the lower limits of the 95% confidence intervals (CIs) ranging from 0.51 to 0.75, and the geometric mean concentration (GMC) ratios for the 23 pneumococcal serotypes ranged from 0.80 to 1.00, with the lower limits of 95% CIs ranging from 0.67 to 0.86. All values met the predefined criteria for non-inferiority. The incidence of adverse events was 0.63% in the C group and 1.56% in the S group. No serious adverse events were observed. In conclusion, the immunogenicity of the concomitant administration of IIV4 and PPSV23 was non-inferior to that of the separate administration, and the safety profile was favorable in adults aged 60 years and older in China.

Background: Low-birth-weight (LBW, <2500 g) infants are at increased risk of suboptimal hepatitis B vaccine responses; yet, data on their immunogenicity patterns and modifiable determinants remain limited. This study aimed to assess hepatitis B vaccine immunogenicity in LBW infants and to examine whether postnatal catch-up growth and maternal–neonatal characteristics are independently associated with antibody levels. Methods: We enrolled 511 LBW infants who completed the recommended 3-dose hepatitis B vaccination series at 0, 1, and 6 months. Blood samples were collected 4–6 weeks after completion of the full vaccination series. Geometric mean concentration (GMC) and seroprotection rate (SPR, anti-HBs ≥ 10 mIU/mL) were evaluated. Catch-up growth was quantified as the change in weight-for-age Z-score between 6 and 8 months of age (ΔWAZ). Multivariable linear regression was used to identify independent predictors of log-transformed antibody titers, adjusting for gestational age, maternal hepatitis B surface antigen (HBsAg) positivity, maternal body mass index (BMI), maternal fasting glucose, maternal thyroid disease, infant hemoglobin at 6 months, and ΔWAZ. Results: The overall SPR was 99.41% (508/511), with a GMC of 1045.37 mIU/mL (95% CI: 916.24–1192.70). SPR remained consistently high across all subgroups. In multivariable analysis, ΔWAZ was not significantly associated with antibody levels (β = −0.063, p = 0.571). Maternal HBsAg positivity showed no significant association (β = −0.104, p = 0.792). Maternal thyroid disease was independently associated with higher antibody levels (β = 0.793, 95% CI: 0.213–1.373, p = 0.007). None of the other covariates reached statistical significance. Conclusions: Hepatitis B vaccination demonstrated high immunogenicity in LBW infants, with very high seroprotection rates. Postnatal catch-up growth did not independently influence antibody levels. The significant positive association between maternal thyroid disease and infant antibody response warrants further prospective investigation.

Background: The inactivated quadrivalent influenza vaccine (IIV4) and the 23-valent pneumococcal polysaccharide vaccine (PPSV23) are widely administered. However, there was limited clinical evidence on the immunogenicity and safety of administration of the two vaccines in individuals with chronic diseases, especially concerning simultaneous administration.Methods: A total of 480 participants aged ≥60 years were randomly assigned to receive simultaneous or separate administration of IIV4 and PPSV23 and categorized into the Chronic Disease group or Healthy group based on their baseline health status. Blood samples were drawn before and 28 days after each vaccination to test the antibodies against all four influenza virus strains and 23 pneumococcus serotypes.Results: The geometric mean titer ratios (Chronic Disease group/Healthy group) of influenza antibodies ranged from 1.04 to 1.37 in the whole population and from 1.02 to 1.39 in the simultaneous administration population. The geometric mean concentration ratios of pneumococcal antibodies ranged from 0.87 to 1.12 in the whole population and from 0.97 to 1.33 in the simultaneous administration population. All ratios met the criteria for non-inferiority. The rate of adverse events was 0.96% in the Chronic Disease group and 1.47% in the Healthy group, with most events being mild (grade 1). No serious adverse events were observed.Conclusion: The immunogenicity and safety profiles of IIV4 and PPSV23, particularly when administered simultaneously, in individuals with chronic diseases were comparable to those in healthy individuals, supporting the vaccination strategy of IIV4 and PPSV23 in chronic disease population.

Background: This study aimed to evaluate the real-world protective effectiveness of the mumps-containing vaccine (MuCV) among children under 15 years of age in Taizhou City, and to analyze the impact of various vaccination-related factors on vaccine effectiveness (VE), so as to provide localized epidemiological evidence for optimizing mumps immunization strategies in children. Methods: A 1:2 matched case-control study was conducted, enrolling 1,405 clinically or laboratory-confirmed mumps cases aged under 15 years in Taizhou City from 2021 to 2025, with 2,810 controls matched by sex, stage of schooling, area of residence, and date of birth. Conditional logistic regression models were used to analyze factors influencing VE. To address sparse data bias, Firth penalized logistic regression sensitivity analyses were additionally performed using R software. Results: The proportion of unvaccinated individuals was significantly higher in the case group (5.3%) than in the control group (0.5%). Receiving at least one dose of MuCV provided a VE of 75.7% (95% CI : 64.8% ~ 83.2%). VE showed an increasing trend with age: no significant protective effect was observed in infants and young children (aged 0 ~ 2 years); for kindergarten children (aged 3 ~ 5 years), VE was 55.2% (95% CI : 22.6% ~ 74.1%); for primary school children (aged 6 ~ 11 years), VE was 86.7% (95% CI: 72.8% ~ 93.5%); and for secondary school children (aged ≥12 years), VE was 92.9% (95% CI : 76.4% ~ 97.9%). However, sparse data bias in the younger age subgroups warrants cautious interpretation. During the single-dose immunization schedule period, VE was 80.4% (95% CI : 70.3% ~ 87.0%), whereas during the two-dose period, no statistically significant protective effect was observed. This result should be interpreted with caution, as the extremely small number of unvaccinated children precluded a reliable assessment of VE, and should not be interpreted as evidence that the two-dose schedule is ineffective. Using unvaccinated individuals as the reference, the P values for the < 18 months and ≥18 months groups were 0.456 and 0.460, respectively, with no statistical significance. Because only 14 unvaccinated controls were available, the OR and VE could not be reliably estimated. The interval between two doses (≤10 months vs. > 10 months) and time since last dose (≤5 years vs. > 5 years) did not show a significant effect on VE (P > 0.05). Due to the limited sample size, these results should be interpreted with caution. Sensitivity analyses and Firth penalized logistic regression analyses yielded results consistent with the main findings, collectively supporting the robustness of our conclusions. Conclusion: MuCV provided significant overall protection against mumps in children under 15 years of age. Subgroup analyses were limited by the extremely high vaccination coverage and the consequent scarcity of unvaccinated individuals. Strengthening vaccination management for infants, young children, and kindergarten children is recommended. Future studies with larger sample sizes and extended follow-up are needed to clarify the incremental value of the two-dose schedule and the pattern of waning immunity.