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.

The global rise in preterm infants presents specific challenges for hepatitis B prevention. Although hepatitis B vaccination is recommended, detailed understanding of immunogenicity patterns and influencing factors requires further investigation. We analyzed 699 preterm infants completing the hepatitis B vaccination series to assess immunogenicity via geometric mean concentration (GMC) and seroprotection rate (SPR). The regimen was highly immunogenic, with an overall SPR of 99.43% (GMC: 986.36 mIU/mL) and 95.28% of infants achieving high-level protection (anti-HBs ≥100 mIU/mL). Though SPR was consistently high across subgroups, notable GMC variations emerged: infants with gestational age <28 weeks markedly higher GMC (3,735.59 mIU/mL) than more mature subgroups. Statistically significant GMC differences were noted between immunization protocols, with uniform schedules yielding higher values (1,281.26 mIU/mL) than mixed approaches (691.91 mIU/mL; P < .001). Preterm infants of HBsAg-positive mothers maintained a high SPR (96.55%) despite a lower GMC (572.18 mIU/mL). This study confirms that hepatitis B vaccination induces a robust immune response at 1 to 2 months post-vaccination in preterm infants. Observed variations in antibody response magnitude related to vaccine expression system may inform optimization of initial vaccination strategies for preterm populations.

Background: This study aimed to investigate the risk factors for mumps in children under 15 years of age during the transition from a single-dose to a two-dose measles–mumps–rubella (MMR) vaccine strategy, providing a scientific basis for public health policies and interventions.Methods: From the China Disease Prevention and Control (CDC) Information System, 547 children aged 0–14 years diagnosed with mumps in Taizhou City between 2021 and 2023 were included as cases. Controls were matched 1:1 and surveyed by the same investigator.Results: The analysis included 547 matched case-control pairs (343 males and 204 females) of children aged <15 years. The median age of the matched case-control pairs was 72 months. Among cases, children aged 49–72 months accounted for the highest proportion (28.52%). The multifactorial study showed that longer local residence (OR = 0.548, 95% CI 0.403 ~ 0.744), history of Mumps Component Vaccine (MuCV) (OR = 0.103, 95% CI 0.036 ~ 0.297), and belief that children would not get mumps (OR = 0.197, 95% CI 0.121 ~ 0.319) reduced the risk of mumps infection. In contrast, families with multiple births (OR = 1.926, 95% CI 1.405 ~ 2.640), being cared by someone other than parents (e.g., grandparents, babysitters, relatives or staff at a childcare center) (OR = 4.366, 95% CI 2.417 ~ 7.888), a higher level of the most frequently visited hospital (OR = 2.012, 95% CI 1.490 ~ 2.716), going into a crowded indoor place without wearing a mask (OR = 1.699, 95% CI 1.237 ~ 2.334), believing that mumps is not an infectious disease (OR = 1.782, 95% CI 1.274 ~ 2.492), believing that the disease is not serious (OR = 1.507, 95% CI 1.260 ~ 1.802), and believing that MuCV cannot prevent mumps (OR = 2.052, 95% CI 1.451 ~ 2.901) increased the risk of mumps infection.Conclusion: For mumps prevention and control, targeted interventions should prioritize children aged 4–6 years and high-risk populations, including short-term residents, multi-child families, and childcare settings. Guardians should be encouraged to gain accurate knowledge about mumps and the protective effects of vaccination to mitigate vaccine hesitancy, ultimately controlling mumps outbreaks in the population.

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: 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.