Background: The steady increase in allergic diseases among children has coincided with increased global vaccination coverage and the expansion of routine childhood immunization programs. This has contributed to the widespread belief that there is a possible link between immunoprophylaxis and allergic diseases. However, a number of scientific studies have demonstrated the protective effect of early neonatal immunization on the development of nonspecific immunological protection against infections. This is believed to be due to a shift in the immune response from the Th2 type, traditionally predominant in newborns, to the Th1 type, which reduces the risk of developing allergic diseases. Methods: This prospective cohort study analyzed the medical records of 2279 children born between 2018 and 2022 to evaluate the impact of neonatal BCG-M and hepatitis B (HepB) vaccination on the incidence of atopic dermatitis (AD) by 36 months of age. Factors analyzed included family history of allergy, cesarean section, prematurity, delayed initiation of breastfeeding, maternal antibiotic use during pregnancy, and antibiotic use in the child during the first three years of life. Results: The cumulative incidence of AD by 36 months of age was 19.9%. Timely neonatal vaccination coverage was 76.2% for BCG-M and 69.2% for HepB; by 12 months of age, these rates increased to 90.2% and 88.5%, respectively. A full-term birth demonstrated a significant protective effect (OR 0.52; 95% CI 0.30–0.93). A positive family history of allergy was the strongest predictor of AD (OR 21.49; 95% CI 14.4–32.9). Cesarean section was also significantly associated with AD (OR 1.30; 95% CI 1.01–1.65). AD incidence was comparable between vaccinated (20.5%) and non-vaccinated (17.5%) children (chi-squared with Yates’ correction, p = 0.192), indicating no statistically significant overall impact of immunization on AD risk. Conclusions: The development of AD is primarily driven by hereditary predisposition and specific perinatal factors rather than by routine immunization. These findings confirm that neonatal BCG-M and HepB vaccination does not increase the risk of AD, providing a scientific basis to address vaccine hesitancy.

Background/Objectives: Bordetella bronchiseptica is a Gram-negative bacterium that, either acting alone or in concert with other bacterial or viral pathogens, is a major cause of the canine infectious respiratory disease (CIRD) complex in dogs. Most currently available vaccines are given intranasally or orally and, whilst providing satisfactory reduction in disease severity, can be difficult to use especially in aggressive or anxious dogs. Whilst a small number of injectable B. bronchiseptica vaccines have been developed, little is known about their characteristics with regard to the age at first vaccination, the onset of immunity, duration of immunity, induction of antibody responses, concurrent use with the core vaccines used in most dogs, efficacy in the face of maternally derived antibodies (MDAs) or existing immunity and safety in pregnant animals. Here we describe the development of a safe and efficacious injectable B. bronchiseptica vaccine that utilises a novel process to purify fimbriae. Methods: The fimbrial antigen was formulated with a vitamin E-based oil-in-water adjuvant known to be safe in dogs (Nobivac® Respira Bb). To evaluate dose response, thirty-nine naïve 5–6-week-old Beagle puppies were allocated to four groups and vaccinated subcutaneously with Nobivac® Respira Bb at 69 U, 25 U, and 7 U (with a booster at two weeks). All groups were challenged with B. bronchiseptica two weeks after the booster. To evaluate the onset of immunity at 5–6 weeks of age, twenty-one naïve Beagle dogs were split into two groups: group 1 received Nobivac Respira Bb (88 U/dose) plus Nobivac DHPPi and Nobivac L4; group 2 received DHPPi and L4 only. Both groups were challenged with B. bronchiseptica two weeks after the second vaccination. Safety in pregnancy was evaluated by vaccinating pregnant dams and monitoring whelping outcomes and puppy health. Protection in puppies with maternally derived antibodies (MDAs) was studied in 28 pups (11 MDA-negative and 17 MDA-positive from vaccinated and unvaccinated dams). Pups were vaccinated at 5–6 weeks; one group remained unvaccinated to monitor MDA kinetics. All puppies were challenged with B. bronchiseptica at 19 weeks, after MDAs became undetectable. Serology was monitored throughout; daily clinical observations and nasal swabs post-challenge assessed protection and bacterial shedding. Results: Nobivac Respira Bb (MSD Animal Health), was safe for use in 5–6-week-old puppies alongside other Nobivac core canine vaccines without vaccine interference. The vaccine has an onset of immunity of two weeks and significantly reduces both the clinical signs of B. bronchiseptica-induced disease and bacterial excretion into the environment. Furthermore, the vaccine is equally efficacious in puppies with maternally derived antibodies derived from vaccinated dams and can be used safely in pregnant bitches. Conclusions: This vaccine represents a convenient, safe and efficacious alternative to vaccines delivered via the oral or intranasal routes and is a positive addition to the range of vaccines targeted at reducing disease induced by B. bronchiseptica.

Background: Since China incorporated the hepatitis B vaccine into its Expanded Program on Immunization (EPI) in 2002, the first cohort of infants to receive the full vaccination series has now reached college age. As vaccine-induced antibodies gradually wane, this cohort faces a higher risk of infection. Therefore, we assessed their current seroprotection status and evaluated the immunogenicity and short-term antibody kinetics of a single 60 μg booster dose in susceptible individuals, while also constructing a model of expected duration of protection. Methods: In a multicenter study across three Anhui universities, 2988 students were screened for HBV markers. Among them, 160 who tested negative for all five markers received a single 60 μg booster. Antibody titers were monitored for 1–5 months. Results: Serological screening showed 0.33% HBsAg positivity, 36.28% anti-HBs positivity, and 63.02% negativity for all markers, indicating high susceptibility. After the booster, seroprotection rate (SPR) remained >85% throughout follow-up, and anti-HBs geometric mean concentration (GMC) peaked at 1–2 months. Stratified analysis based on immune response status revealed that the proportion of high responders (≥100 mIU/mL) peaked early and then gradually declined, whereas the proportion of low responders (10–99.99 mIU/mL) increased over the follow-up period. A linear mixed-effects model predicted that protective levels (anti-HBs ≥10 mIU/mL) would persist for an average of 32.8 months. Conclusions: A substantial proportion of university students lack protective immunity against hepatitis B. A single 60 μg booster rapidly and effectively induced protection, demonstrating strong immunogenicity. These findings support implementing efficient booster strategies in university settings.

Background/Objectives: Poorly soluble aluminium (Al) compounds have successfully been used for decades as adjuvants in vaccines, enabling an effective immune response. Yet the safety of Al exposure from vaccines is consistently questioned, especially regarding infants. Since toxicokinetic data of aluminium after vaccination in humans are not available, model-informed predictions are needed for risk assessment. Methods: Using a physiologically-based toxicokinetic model, we predicted the Al exposure from i.m. injections of Al-adjuvanted vaccines for full-term neonates to 50-year-old adults following the recommended vaccination schedule in Germany 2025 in addition to the continuous oral background Al exposure from dietary intake. Results: During the first two years of life, moderate (max. 2-to-3-fold) but transient increases of Al concentrations in plasma and in the relevant target organs liver and bone due to vaccinations were predicted. Increase in brain Al content was 4%. Most importantly, in all tissues, maximum Al levels did not exceed normal levels observed in infants soon after birth or known from adults. In children and adults, the rise in Al concentrations in plasma and tissues due to single vaccinations was marginal. The calculated contribution of vaccinations to the Al body burden at age 50 was negligible. Conclusions: From a toxicokinetic perspective, the additional Al exposure in full-term infants, children and adults from vaccinations with Al-adjuvanted vaccines according to the current recommended schedules is considered safe. The model has proven a valuable tool for predictions of Al exposure from vaccinations.

Background: Influenza causes substantial morbidity in young children, particularly those aged 6–35 months. In this age group, optimisation of vaccine dose regimens remains important to ensure adequate immunogenicity while maintaining acceptable safety. This study evaluated the immunogenicity and safety of a full 0.5 mL dose of quadrivalent inactivated influenza vaccine (NBP607-QIV) in young children. Methods: This Phase 3, randomised, double-blind, active-controlled, multicentre study was conducted in Korea, Thailand, and Malaysia. Healthy children aged 6–35 months were randomised 2:1 to receive NBP607-QIV (0.5 mL) or control vaccine (0.25 mL). Immunogenicity was assessed using the haemagglutination inhibition assay. Primary endpoints were non-inferiority of NBP607-QIV versus Agrippal for seroconversion rate (SCR) and adjusted post-vaccination geometric mean titre (GMT) ratio against three shared strains. Immunogenicity against the additional B/Yamagata strain was evaluated according to Committee for Medicinal Products for Human Use (CHMP) criteria. Safety was assessed based on adverse events. Results: A total of 676 participants were randomised, and 675 were included in the safety set. Non-inferiority of NBP607-QIV versus control vaccine was demonstrated for SCR for all shared strains and for the adjusted GMT ratio for A/H1N1 and B/Victoria, but not for A/H3N2. Immunogenicity against the B/Yamagata strain met CHMP criteria for SCR and geometric mean ratio (GMR). Immunogenicity was consistent across prespecified subgroups, and the incidence of adverse events was comparable between groups, with no clinically meaningful safety concerns. Conclusions: NBP607-QIV administered at a 0.5 mL dose demonstrated acceptable immunogenicity and a safety profile comparable to that of a licensed trivalent influenza vaccine in children aged 6–35 months, supporting its use in this paediatric population.

Background: The 2024/25 influenza season in Hungary experienced a major surge in cases, the largest since the COVID-19 pandemic. We evaluated influenza vaccine effectiveness (VE) in primary care settings among adults and vaccination target groups, and also according to time since vaccination, prior seasonal vaccination, and influenza type. Methods: A test-negative case–control study was conducted in Hungary. Data and specimens were collected from primary care patients with an acute respiratory infection (ARI). Patients with positive PCR test results for influenza were classified as cases, while those with negative test results for influenza were classified as controls. Adjusted VEs were calculated using logistic regression as (1−odds ratio of vaccination) ×100. Results: Between November 2024 and May 2025, 2074 patients were included in the analysis, of whom 395 cases had influenza. Of the 129 vaccinated patients, 123 (95%) received trivalent inactivated adjuvanted whole-cell vaccine (TIAV), and 6 (5%) received quadrivalent split-virion vaccine. The VE against any influenza was 53% (95% CI: 13–74) in the 18+ age group and 52% (95% CI: 7–75) in the target group for vaccination. The VE against any influenza was 63% (95%CI: 17–84) 14–89 days after vaccination, and 27% (95%CI: −67–68) 90 days or more after vaccination. The VE against any influenza was 56% (95%CI: 1–80) with both current and prior seasonal vaccination, and 5% (95%CI: −64–45) with only prior seasonal vaccination. The VE against influenza A was 39% (95%CI: −16–68), and against influenza B was 80% (95%CI: 2–96). Conclusions: We observed moderate vaccine effectiveness against any influenza, with higher protection within three months after vaccination. Our research findings provide evidence to inform the development of vaccines and the scheduling of vaccination campaigns, with the aim of maximizing the level of protection provided by vaccines throughout the entire influenza season.

Background: Parents serve as the primary decision-makers for childhood vaccination while also making decisions regarding their own vaccination, yet vaccination decision drivers are typically studied separately by vaccine type or target population. Methods: This study investigated parental decision-making processes for two self-paid and non-National Immunization Program vaccines in China, childhood rotavirus vaccine and adult influenza vaccine, by utilizing a structured survey grounded in the World Health Organization Behavioral and Social Drivers of Vaccination framework. Spearman’s rank correlation coefficients were used to assess the consistency of parental attitudes toward the two vaccines across behavioral and social driver domains. Structural equation models were conducted separately for childhood and adult vaccines to examine decision-making pathways. Results: The findings indicated that parental drivers related to awareness, social processes, and practical issues showed a high consistency across adult and childhood vaccination decisions (r > 0.7), whereas the consistency in vaccination behaviors remained low (r = 0.21). Compared with adult vaccination, childhood vaccination decisions were more strongly influenced by vaccine safety concerns and healthcare practitioners’ recommendations, which emerged as key drivers. Furthermore, family norms emerged as an effectively shared driver of vaccination decisions for both adult and childhood vaccines (adult: β = 0.784; childhood: β = 0.970). Conclusions: By jointly synthesizing adult and childhood vaccination decisions from a parental perspective, this study provides crucial evidence to support the development of integrated, family-centered strategies to improve vaccine uptake.

Background: Annual influenza vaccination is a WHO-recommended strategy for preventing seasonal influenza and its associated severe complications in older adults. Nevertheless, influenza vaccine effectiveness is often reduced in the elderly population and there remains an ongoing debate regarding whether repeated vaccination attenuates immune response. Methods: We conducted a prospective observational study to estimate the trivalent inactivated influenza vaccine-induced antibodies in older adults vaccinated for two consecutive years (2022–2023 and 2023–2024) and those with vaccines administered in a single season (2023–2024). Serum samples were collected concurrently with vaccination and at 30 and 90/180 days post-vaccination for hemagglutination inhibition (HAI) tests. Results: The participants administered two consecutive vaccinations had markedly higher pre-vaccination geometric mean titers (GMTs) and seroprotection rates for influenza A/H1N1 and A/H3N2. However, no intergroup differences were observed for H1N1, H3N2 or B/Victoria strains at 30, 90, or 180 days post-vaccination. At 30 days post-vaccination, participants with two consecutive influenza vaccinations showed significantly lower fold rises against the three strains and seroconversion rates (SCRs) for H1N1 and H3N2. The results of the subgroup analyses were largely consistent with the primary findings, with the exception of the A/H1N1 strain among individuals with pre-vaccination titers <1:10 at day 30. Conclusions: Immune responses vary by antigen type, and the influenza vaccine induces comparable serological response in the elderly, irrespective of their prior vaccination history.

Background: People living with HIV (PLWH) constitute a vulnerable population during the COVID-19 pandemic; however, it remains uncertain whether long-term suppressive antiretroviral therapy (ART) restores sufficient immune competence to support robust hybrid immunity. While vaccination followed by breakthrough infection—termed hybrid immunity—typically elicits potent humoral responses in immunocompetent individuals, the functional quality and breadth of these responses against evolving Omicron subvariants remain poorly characterized in PLWH. This study aimed to assess functional antibody responses, including neutralizing activity and Fc effector functions, in vaccinated and unvaccinated PLWH who experienced breakthrough infection with Omicron subvariants BA.4/5 or BF.7. Methods: We enrolled three cohorts between December 5 and December 20, 2022: 25 HIV-negative individuals with breakthrough infection (BTI-HC), 20 ART-experienced PLWH with breakthrough infection following three-dose COVID-19 vaccination (BTI-HIV), and 10 ART-experienced PLWH with primary infection without prior vaccination (PI-HIV). All HIV-positive participants were receiving suppressive ART with regimens based on non-nucleoside reverse transcriptase inhibitors or integrase strand transfer inhibitors for a median of 3.4 years. We measured receptor-binding domain (RBD)-specific IgG, neutralizing antibody titers against ancestral D614G, Delta, BA.1, BA.4/5, BF.7, XDV, KP.2, and KP.3 variants, and antibody-dependent cellular cytotoxicity (ADCC) responses. Results: Despite lower absolute CD4+ T cell counts, BTI-HIV participants mounted RBD-binding IgG, neutralizing antibody, and ADCC responses that were comparable to BTI-HC and significantly exceeded PI-HIV across all tested variants. Both breakthrough infection cohorts exhibited immunological imprinting, with higher neutralizing titers against ancestral D614G than infecting BA.4/5 or BF.7 variants. Emerging variants XDV, KP.2, and KP.3 demonstrated substantial neutralization escape in all groups. PI-HIV showed markedly diminished neutralization breadth and failed to generate enough responses against all tested Omicron strains. Conclusions: Suppressive ART enables PLWH to mount hybrid immunity—conferred by vaccination followed by BF.7 or BA.4/5 breakthrough infection—with neutralizing and ADCC responses comparable to HIV-negative individuals, and significantly exceeding those of unvaccinated PLWH with primary infection. This underscores the critical role of vaccination in establishing effective hybrid immunity in this population. However, we observed immunological imprinting, with higher titers against ancestral strains than against infecting variants, and substantial escape by emerging sublineages XDV, KP.2, and KP.3 across all groups. These findings support prioritizing updated variant-containing vaccines for HIV-positive populations and reinforce the essential role of vaccination in this vulnerable group.

Background/Objectives: Bovine viral diarrhea (BVD) is a major infectious disease of cattle caused by bovine viral diarrhea virus genotypes 1 and 2 (BVDV-1 and BVDV-2). Current inactivated and live attenuated vaccines provide incomplete cross-genotype protection and may exhibit limitations related to durability of immunity or safety. This study evaluated whether co-expression of the BVDV envelope glycoproteins E1 and E2 in a Modified Vaccinia Ankara (MVA) vector could support antigen expression and induce immune responses in a proof-of-concept model. Methods: Recombinant Modified Vaccinia Ankara (MVA) viruses expressing BVDV-1 E1E2 or BVDV-2 E1E2 were generated by homologous recombination. Recombinant viruses were purified and characterized for antigen expression, genetic stability, and growth properties in vitro. Immunogenicity was evaluated in a BALB/c mouse model by measuring E2-specific antibody responses, virus-neutralizing antibodies, and antigen-responsive cellular immune responses. Results: Both recombinant MVA constructs showed detectable E2 expression when E1 and E2 were co-expressed, and exhibited growth characteristics comparable to parental MVA with stable maintenance after serial passage. In contrast, recombinant MVA expressing E2 alone did not yield detectable E2 protein under the same experimental conditions. Immunization induced detectable humoral and cellular immune responses, including E2-specific IgG antibodies, virus-neutralizing antibodies, and increased frequencies of antigen-responsive CD8+ T cells with a tendency toward a Th1-biased profile. Conclusions: These findings indicate that co-expression of BVDV E1 and E2 in an MVA vector can support detectable antigen expression and induce measurable immune responses in a mouse proof-of-concept model. Further studies in cattle, including challenge experiments, will be required to determine the protective efficacy and practical applicability of this platform for BVDV vaccine development.