Search Results (144)

Background: Despite its high vaccination coverage, pertussis remains a public health concern due to waning vaccine-induced immunity and the emergence of pertactin (Prn)-negative strains. Nevertheless, anti-Prn antibodies and memory B cells elicited by vaccinations may contribute to long-term immunity and protection against Prn-positive strains. While most vaccination studies focus on serum antibodies, data on memory B cells remain limited. Methods: In this study, we implemented a flow cytometry-based approach to characterize Prn-specific B-cell fluctuations following Tdap booster vaccination in five healthy adults. Total and Prn- and tetanus toxoid fragment C (TTC)-specific plasma cells and memory B cells were analyzed at baseline and at 7, 14, 21, and 90 days post-vaccination using Prn Klickmers^® and TTC tetramers. Following this, cellular responses were correlated with antigen-specific serum IgG and IgA levels. Results: Prn-specific and TTC-specific memory B cells increased on days 14 and 7 post-vaccination, respectively, accompanied by a phenotypic shift from IgMD+ to IgG+ cells. Clear expansions of total as well as Prn- and TTC-specific plasma cells occurred on day 7. These plasma cells primarily comprised IgG+, but an increase in Prn-specific IgA+ plasma cells was also observed. The numbers of Prn-specific IgG+ memory B cells on day 7 post-vaccination correlated weakly with serum anti-Prn IgG levels at later time points. Conclusion: To our knowledge, this is the first study to use flow cytometry to evaluate Prn-specific B-cell responses and report their fluctuations over time following vaccination. These findings support the potential of this method to complement serological assays and improve our understanding of vaccine-induced immunity. Full article

Tetanus is a zoonotic disease posing significant threats to both humans and animals, particularly horses, sheep, and ruminants. Current antitoxin therapies rely on animal-derived immunoglobulins, presenting challenges including animal welfare concerns, pathogen contamination risks, and manufacturing complexity. Alpaca-derived nanobodies (VHH) are promising alternatives owing to their high antigen-binding affinity, thermostability, and potential for microbial production. We developed highly active trivalent VHH antibodies (tVHH) that target multiple epitopes of tetanus neurotoxin (TeNT). Following alpaca immunization with tetanus toxoid, 41 VHH clones were isolated using phage display. Six VHH clones were selected through in vivo neutralization assays, from which three clones of VHH (8, 11, 36) were selected to construct tVHH-8/11/36 and tVHH-8/36/11. Using an improved 21-day mouse neutralization assay, tVHH-8/11/36 demonstrated exceptional neutralizing activity of approximately 1580 IU/mg against 4000 LD₅₀ of toxin, substantially exceeding current human and veterinary anti-tetanus immunoglobulin preparations. Surface plasmon resonance and ELISA confirmed that each VHH recognizes different TeNT domains, producing synergistic neutralizing effects through multimerization. Since antitoxin therapy challenges are common to both animals and humans, this tVHH technology supports One Health by providing a unified therapeutic platform applicable across species through sustainable microbial production. Full article

No vaccines are licensed against enterotoxigenic Escherichia coli (ETEC), a leading diarrheal cause in children and travelers. ETEC adhesins and enterotoxins are the virulence determinants and become the primary targets in ETEC vaccine development. However, ETEC strains produce > 25 adhesins and two potent enterotoxins, particularly the poorly immunogenic heat-stable toxin (STa), greatly hindering ETEC vaccine development. To overcome these challenges, we developed a multiepitope-fusion-antigen (MEFA) platform. MEFA presented multiple adhesin epitopes on a backbone and generated a polyvalent adhesin immunogen, CFA/I/II/IV MEF. CFA/I/II/IV protected against the seven ETEC adhesins (CFA/I, CS1-CS6) associated with two-thirds of ETEC diarrheal cases. We further used toxoids as safe antigens and created a toxoid fusion, 3xSTa_N12S-mnLT_R192G/L211A. This antigen induced antibodies neutralizing the enterotoxicity of STa and heat-labile toxin (LT), which, alone or together, cause all ETEC diarrheal cases. By combining two polyvalent proteins, we developed a multivalent ETEC vaccine, MecVax, that protects against seven ETEC adhesins and two enterotoxins. MecVax is broadly immunogenic. MecVax prevents intestinal colonization by ETEC strains expressing any of the seven adhesins and protects against clinical diarrhea from ETEC strains producing LT or STa enterotoxin preclinically, becoming a broadly protective ETEC vaccine candidate against children’s diarrhea and travelers’ diarrhea. Full article

Background: During pregnancy, mothers and their infants are at increased risk for complications due to COVID-19 infection, influenza, and pertussis. At the time of writing, the previous advisory committee on immunization practices (ACIP) recommended that pregnant women receive the COVID-19 vaccine, influenza, tetanus-toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine, as well as respiratory syncytial virus vaccinations during pregnancy. The COVID-19 pandemic greatly impacted routine vaccinations especially among medically underserved women in the South. The barriers to recommended vaccinations during pregnancy for medically underserved women in the South are unclear and require further investigation. The purpose of this study is to examine the attitudes, opinions, and beliefs of a multiracial pregnant cohort from diverse backgrounds in Central Tennessee about their experiences with the vaccines that are recommended during pregnancy. The vaccines included in the study are COVID-19, flu, and Tdap because RSV was not yet FDA-approved for pregnant women at the launch of this study. Methods: In this study, we focus on medically underserved women in Nashville, Tennessee, and the surrounding rural counties regarding vaccine acceptance and initiation of the COVID-19, influenza, and the Tdap vaccines. This study involved 208 pregnant people (100%) aged 18–49 years. All respondents were pregnant at the time of the study. The study consisted of a 26 question Redcap survey about participants’ beliefs, attitudes, opinions, and experiences with the COVID-19, flu, and Tdap vaccines during their pregnancy. Results: The randomly selected participants in the cohort were 40.4% White, 31.7% Black, 21.6% Hispanic, and 6.3% other race/ethnicity. The mothers in the cohort were young, with an average age of 27 years, most were married, and 52.8% had an annual household income before taxes of less than USD 35,000. Only 19.2% of the mothers in this study were very confident of the safety of the COVID-19 vaccine, compared to 32.7% for both the flu and Tdap vaccines. Overall, primary care providers were identified as the most trusted messengers for both disease and vaccine information for COVID-19, flu, and Tdap. However, only 11 participants out of 208 received all three of the ACIP recommended vaccines during their pregnancies in the study, barring the time-dependent vaccination for Tdap. The most common reasons for not receiving these vaccines involved concerns for the safety of themselves and their babies and a fear of needles. Conclusions: Education and awareness of ACIP-recommended vaccines during pregnancy needs improvement, and the support of primary care providers as the main driver of pregnancy vaccine initiation is essential. Full article

Haemophilus influenzae type b (Hib) is a Gram-negative bacterium that causes severe infections in children under five, especially in developing countries. Although vaccination using capsular polysaccharide by Hib (linear polymer 5-D-ribitol-(1→1)-β-D-ribose-3-phosphate) conjugated to tetanus toxoid is effective, its production is complex and costly. This study aimed to develop a continuous production process for PRP to increase productivity, reduce batch numbers, and simplify manufacturing. Using a 1 L bioreactor, five dilution rates (0.13 to 0.32 h⁻¹) were tested, with the best performance observed at 0.23 h⁻¹, reaching a productivity of 167 mgL⁻¹·h⁻¹. Under optimized conditions, parameters such as free and immobilized PRP, glucose consumption, acetate formation, and biomass were monitored. The process yielded 874 mgL⁻¹ of PRP after 74.4 h, with 78% in the free form and a final productivity of 165 mgL⁻¹·h⁻¹, approximately six times higher than batch processes and twice as high as fed-batch processes. The continuous process proved more efficient and required less infrastructure to meet production demands. However, further optimization is needed to enhance product quality and assess overall feasibility. Full article

Background: Common variable immunodeficiency (CVID), the most prevalent symptomatic inborn error of immunity, involves impaired B-cell differentiation and antibody production, causing recurrent infections and the need for life-long immunoglobulin replacement therapy. Methods: This study evaluated the in vitro differentiation of memory B-cells (MBCs) into antibody-secreting cells (ASCs) in CVID patients. Peripheral blood mononuclear cells from 13 CVID patients and 10 healthy controls were stimulated using two protocols: (I) Staphylococcus aureus Cowan Strain I, Pokeweed mitogen, and CpG, or (II) a T-cell-dependent approach using CD40 ligand, interleukin-21, and CpG. B-cell subpopulations were analyzed by flow cytometry, ASC differentiation using ELISpot, and antibody levels in supernatants by ELISA. Results: Despite severely restricted in vivo antibody production, MBCs from all 13 CVID patients differentiated into IgG and IgM ASCs under adequate in vitro stimulation. Protocol II, mimicking T-cell help, was more effective than protocol I. As expected, the patients exhibited reduced class-switched MBCs ex vivo, but the MBCs differentiated and proliferated to an extent similar to those in healthy controls. IgA secretion remained significantly impaired post-stimulation. Specific IgG antibodies against tetanus toxoid and Streptococcus pneumoniae were detected in the patient supernatants, while no double-stranded DNA autoantibodies emerged after in vitro stimulation. Conclusions: These findings indicate that the MBCs of most patients retain functional B-cell differentiation and antigen-specific IgG secretion under T-cell dependent stimulation, though IgA secretion remains impaired. Tailored stimulation protocols could deepen our understanding of how to restore MBC formation in CVID patients in vivo. This methodology provides a platform to investigate antigen-specific functional memory responses like post-vaccination. Full article

Vaccine quality control has long relied on animal testing, which involves time, cost, and ethical constraints. This study introduces a ganglioside binding (GB) assay as a complementary in vitro screening tool for tetanus toxoid quality control, which was validated in a single-laboratory environment as a foundational proof-of-concept. The assay reproduces tetanus toxin binding to gangliosides on microplates using simplified procedures. Validation with samples at different inactivation stages showed excellent linearity (0.0002–0.0156 Lf/mL), reproducibility, and a strong correlation with Ramon’s flocculation (R² = 0.999). The assay clearly distinguished between toxins and toxoids, with the toxoid results remaining at control levels. The time-course inactivation samples were consistent with the animal tests: partially inactivated samples (days 1–3) showed significant GB activity (p < 0.001) and caused 100% mortality, whereas samples from day 4 onward showed no activity and zero mortality. These findings demonstrate that the GB assay reliably differentiates active toxins from toxoids, which aligns with in vivo outcomes. The practical advantages include a simplified protocol, reduced complexity, and improved efficiency for routine testing of samples. As a complementary screening approach, this single-laboratory validation supports the 3Rs principle by demonstrating the potential for reducing animal use while ensuring quality assurance. Broader applicability requires multicenter validation and cross-reactivity, and multicenter validation is ongoing. Full article

Background: In Vietnam, the Ministry of Health recently approved the use of Tdap vaccines—Boostrix (2022) and Adacel (2024)—for administration during pregnancy, aiming to provide passive antibody transfer to protect newborns against pertussis and tetanus from birth. However, uptake remains low, largely because Tdap is not included in the National Expanded Program on Immunization, vaccine hesitancy persists among obstetricians, and local safety data in pregnancy are limited. Methods: We conducted a prospective cohort study from September 2023 to September 2024 involving 485 pregnant women between 27 and 36 weeks of gestation at two major hospitals in Ho Chi Minh City: University Medical Center and Gia Dinh People’s Hospital. Participants received either Tdap or monovalent tetanus toxoid vaccine (TT) as a comparator. Results: Among women in the Tdap group, 49.8% reported at least one adverse event following immunization (AEFI). Local reactions were the most frequent, primarily injection-site pain (43.8%). Fatigue (12.8%) was the most common systemic reaction, followed by headache (3.9%). Grade 3 AEFIs occurred in 5% of the Tdap group and included extensive local reactions (erythema or swelling > 3 cm), high-grade fever (≥40 °C), and severe fatigue interfering with daily activities or requiring hospitalization. Women receiving Tdap had 1.52-fold higher injection-site pain compared with those receiving TT (95% CI: 0.060–0.782). Importantly, co-administration of Tdap with inactivated quadrivalent influenza vaccine (IIV4) did not increase the risk of AEFIs. Furthermore, no evidence was found that Tdap vaccination adversely affected the course of pre-existing maternal comorbidities, which remained stable throughout pregnancy. Conclusions: This first large-scale Vietnamese cohort provides reassuring evidence on the safety of Tdap vaccination during pregnancy. These findings support broader implementation of maternal Tdap immunization, including concomitant administration with IIV4, to protect both mothers and infants. Full article

This study focused on utilizing the double-mutant heat-labile toxin (R192G/L211A) (dmLT) as a backbone protein, into which neutralizing epitopes of ETEC (FaeG, FedF, FanC, FasA, and Fim41a) were embedded. A combination of computational modeling and immunogenicity analysis was conducted to evaluate the dmLT_{(R192G/L211A)} multiepitope fusion antigen (MEFA). Both the computational modeling and experimental results confirmed that all relevant epitopes were clearly exposed on the surface of the MEFA. Subcutaneous immunizations of rabbits with the MEFA protein yielded the development of IgG antibodies that targeted all five fimbriae. Furthermore, these antibodies demonstrated significant inhibition of adhesion for K88+, K99+, 987P+, F18+, and F41+ ETEC strains to porcine small intestinal epithelial cell line IPEC-J2 cells. These results indicated that the dmLT toxoid-based MEFA protein effectively elicits high-titer, functional antibodies capable of neutralizing the attachment of multiple prevalent ETEC fimbrial types, highlighting its potential as a broad-spectrum vaccine candidate. Consequently, it shows promising potential as a broad and effective vaccine against ETEC. Full article

Background: The persistence of non-neonatal tetanus (non-NT) highlights the necessity of adult booster vaccines and post-traumatic prophylaxis. This Phase I/III clinical trial aimed to evaluate the safety and immunogenicity of a new adsorbed tetanus vaccine. Methods: A randomized, double-blind, positive-controlled clinical trial was conducted in Henan Province, China. A total of 1258 healthy participants aged 18–44 years (60 in Phase I and 1198 in Phase III) were enrolled, with no history of tetanus infection, or tetanus toxoid-containing vaccines (TTCVs) vaccination within the past 10 years. The participants were randomly assigned at a 1:1 ratio to receive a single dose of either the investigational vaccine or the licensed control vaccine. The Phase III clinical trial was initiated subsequent to the 7-day safety observation period following vaccination in the Phase I trial. The objective of the Phase III clinical trial was to assess the non-inferiority of the seroconversion rate of tetanus antibodies at 30 days post-vaccination with the investigational vaccine compared to the control vaccine. Serum samples were collected prior to and at 30 days post-vaccination. Adverse events were monitored for 30 days, with serious adverse events (SAEs) followed up for 6 months post-vaccination. Results: The investigational group achieved a seroconversion rate of 99.48%, which was non-inferior to that of the control group (99.66%), with a negligible rate difference of −0.17% (95% confidence interval [CI]: −1.20%, 0.78%). The investigational group exhibited a significantly higher geometric mean concentration (GMC) of antibodies (4.721 IU/mL vs. 3.627 IU/mL, p < 0.0001). Among the susceptible participants, the seroconversion rates were 99.78% in the investigational group and 99.79% in the control group, respectively, with a non-inferior rate difference of −0.01% (95%CI: −1.06%, 0.97%). Furthermore, the investigational group showed a low incidence of adverse reactions (ARs) within 30 days post-vaccination (12.26%), which was comparable to that of the control group (13.65%). All the reported ARs were mild or moderate, and no SAEs were associated with the vaccination. Conclusions: The new adsorbed tetanus vaccine demonstrated favorable safety and comparable immunogenicity to the marketed control vaccine, with a significantly higher antibody GMC, supporting its clinical application in tetanus prevention. Full article

Background/Objectives: Hypercholesterolemia remains a major risk factor for cardiovascular disease and a leading cause of global mortality. Proprotein convertase subtilisin/kexin type 9 (PCSK9) promotes degradation of low-density lipoprotein receptors (LDLR), thereby reducing LDL-cholesterol (LDL-C) clearance. While monoclonal antibodies (mAbs) targeting PCSK9 are effective, their short half-life requires frequent dosing and incurs high treatment costs. This study evaluates a novel peptide-based Anti-PCSK9 product aimed at providing sustained LDL-C reduction. Methods: A novel PCSK9 based-peptide conjugated to diphtheria toxoid (DT) was evaluated in various preclinical models: high-fat diet-fed C57BL/6 mice, APOB100/hCETP transgenic mice, BALB/c mice and normocholesterolemic non-human primates. Immunogenicity (Anti-PCSK9 antibody titers, binding affinity by SPR), pharmacodynamics (LDL-C levels, inhibition of PCSK9-LDLR interaction) and safety were assessed. Toxicity was evaluated in rodents, rabbits and dogs through clinical monitoring, histopathology, organ function and safety pharmacology studies. Results: The Anti-PCSK9 product induced robust and long-lasting immune response in all models antibody titers in BALB/c mice peaked by week 6 and persisted for 12 months. LDL-C reductions of 44% in APOB100/hCETP mice and 37% in C57BL/6 mice correlated with high antibody titers and strong PCSK9-binding affinities (85 and 49 RU), leading to 59% and 58% inhibition of PCSK9-LDLR interaction, respectively. Non-human primates showed sustained responses. No systemic toxicity was observed; injection-site reactions were mild and reversible. No adverse effects were detected on cardiovascular, neurological, or respiratory systems. Conclusions: This peptide-based Anti-PCSK9 therapy offers sustained efficacy and safety, representing a promising long-acting alternative for managing hypercholesterolemia. Full article

The impact of Oedema Disease produced by Shiga toxigenic Escherichia coli (STEC) in swine is increasing in some production countries due to increasing limitations on treatment with antimicrobials and zinc oxide, either because of the increased prevalence of multi-resistant strains or because of legal restrictions. The main pathological effect of Shiga toxin 2e is represented by damage to the endothelial cells of the blood vessel walls, leading to liquid extravasation and oedema formation in multiple tissues. These oedemas are generally easily identifiable in acute clinical cases. However, disease caused by Shiga toxin can occur without any externally visible oedema in the pigs, as observed in the subclinical presentation of Oedema Disease. It also causes productive losses, so it is important to identify and/or diagnose cases to set up control measures in order to optimize production and health. This article includes a comprehensive review of lesions and signs caused by Shiga toxin toxicosis in pigs, as well as other insights about the aetiology and epidemiology of STEC in pigs, and the effect of Shiga toxin recombinant toxoid vaccines in reducing these clinical and subclinical signs under field conditions. Full article

Background/Objectives: Chemically or genetically detoxified pertussis toxin (PTx) is a crucial antigen component of the acellular pertussis vaccine. Chemical detoxification using glutaraldehyde generally causes significant structural changes to the toxin. However, how these structural changes in PTx affect its antigenic properties remains unclear. Additionally, there is limited knowledge regarding how many alterations in antigenic properties impact immunogenicity. Methods: To investigate the impact of structural changes on antigenic properties, we developed a sandwich ELISA to quantify the neutralizing epitopes on PTx. Subsequently, we analyzed different PTx toxoid (PTd) preparations with the assay. Additionally, we assessed the immunogenicity of various acellular pertussis vaccine candidates containing these PTd preparations. Finally, the assay was applied to evaluate the consistency of commercial batches of PTx and PTd intermediates. Results: The assay demonstrated reasonable specificity, accuracy, and precision, and it was sensitive enough to quantify variations in neutralizing epitopes among different PTd samples that shared the same protein concentration. Importantly, we found a positive correlation between the number of neutralizing epitopes in detoxified PTx and its immunogenicity, indicating that the amount of neutralizing epitopes present determines the immunogenicity of glutaraldehyde-inactivated PTx. Moreover, commercial batches of PTx and PTd intermediates exhibited minor variations in neutralizing epitopes. Conclusions: These findings have significant implications for developing acellular pertussis vaccines as they highlight the importance of preserving the neutralizing epitopes of PTx during detoxification to ensure the vaccine’s effectiveness. This assay is also valuable for the quality control of PTd as it more accurately represents the actual antigenic changes of PTx. Full article

Tetanus is a life-threatening, vaccine-preventable disease caused by tetanospasmin and tetanolysin, which are potent neurotoxins produced by Clostridium tetani, an anaerobic, spore-forming bacterium. Due to the widespread presence of spores in the environment, the disease cannot be eradicated. However, global tetanus prevention initiatives have contributed to a significant decline in tetanus incidence worldwide. Aiming to present the tetanus trends in Romania, we conducted a retrospective analysis of the tetanus surveillance data. During the study period (2010–2023), 97 cases of tetanus were reported in Romania (median: 6.5; IQR: 5–7) with an average incidence rate of 0.03 per 100,000 inhabitants (95% CI: 0.02–0.04; range: 0.01–0.09). The highest incidence rates were recorded among people aged 1 to 14 years old (0.09 per 100,000 inhabitants, 95% CI: 0.06–0.13; range: 0.00–0.20), male (0.05 per 100,000 inhabitants; 95% CI: 0.03–0.06; range: 0.03–0.12), and from rural areas (0.05 per 100,000 inhabitants; 95% CI: 0.03–0.08; range: 0.01–0.17). A decline in the number of tetanus cases of 7% by year was observed, which is supported by the statistical analysis showing a p-value of 0.005 (IRR: 0.93; 95% CI: 0.88–0.98). However, the same decline in tetanus incidence was not supported by the statistical analysis (IRR: 0.93; 95% CI: 0.44–1.98; p = 0.9). Forty-seven tetanus deaths were recorded, with an average case fatality ratio of 42% (95% CI: 25.62–57.92; range: 0–100), showing a decreasing trend of 9% by year (IRR: 0.91; 95% CI: 0.89–0.93). Although the annual number of tetanus cases in Romania has shown a slight downwards trend, its situation has remained relatively stable, as shown by the tetanus incidence. Moreover, the case fatality rate continues to be high. Therefore, our study emphasizes the importance of achieving high vaccination uptake among children and adolescents, raising awareness of the importance of booster doses in adults, and improving the management of tetanus-prone wounds. Full article

Background: The combined diphtheria–tetanus–acellular pertussis (three-component), Haemophilus influenzae type b (Hib, conjugate), and ACYW135 meningococcal (conjugate) vaccine (DTaP-Hib-MCV4) offers a promising alternative to single-component vaccines, potentially simplifying immunization schedules and improving vaccination coverage. Methods: We evaluated the safety, immunogenicity, and protective efficacy of DTaP-Hib-MCV4 in animal models. Acute and long-term toxicity studies were conducted in Sprague-Dawley (SD) rats with equal numbers of male and female animals. Immunogenicity was assessed in female NIH mice and SD rats using a three-dose regimen at 14-day intervals. Orbital blood was collected 14 days post-immunization to measure IgG titers against pertussis, diphtheria, tetanus, Hib, and meningococcal antigens. The protective efficacy was determined using potency tests for the pertussis, diphtheria, and tetanus components; passive protection studies for Hib; and serum bactericidal antibody (SBA) titers against A/C/Y/W135 meningococcal serogroups. Results: Acute and repeated-dose toxicity studies in SD rats showed no signs of abnormal toxicity or irritation at either high (three doses/rat) or low (one dose/rat) doses levels. The no-observed-adverse-effect level (NOAEL) for DTaP-Hib-MCV4 was established at three doses/rat after 8 weeks of repeated intramuscular administration and a 4-week recovery period. Specific IgG antibodies against all the vaccine components were detected in animal sera at both one and three doses/rat, with no evidence of immunotoxicity. Following two-dose primary immunization in murine models, the combined vaccine elicited robust antigen-specific antibody responses, with geometric mean titers (GMTs) as follows: 1,280,000 for pertussis toxin (PT); 761,093 for filamentous hemagglutinin (FHA); 1,159,326 for pertactin (PRN); 1,659,955 for diphtheria toxoid (DT); 1,522,185 for tetanus toxoid (TT); 99 for Haemophilus influenzae type b (Hib); and 25,600, 33,199, 8300, and 9051 for serogroups A, C, Y, and W135 of Neisseria meningitidis, respectively. In the rat models, three-dose primary immunization also elicited robust antigen-specific antibody responses. Protection studies demonstrated efficacy against pertussis, tetanus toxin, and diphtheria toxin challenges. In the Hib challenge study, none of the 10 animals given anti-DTaP-Hib-MCV4 antiserum developed bacteremia after the live Hib challenge (vs. 5814/0.1 mL in the negative control, p < 0.001). In addition, the SBA titers against meningococcal serogroups exceeded the protective threshold (≥1:8) in 92.2% of the immunized mice and 100% of the immunized rats. Crucially, the combined vaccine induced potent immune responses and protective efficacy, with antibody levels and protection against each component antigen comparable to or greater than those of the individual components: DTaP, Hib, and MCV4. Conclusions: These findings demonstrate that the DTaP-Hib-MCV4 combined vaccine is both safe and immunogenic, supporting its potential as a viable alternative to individual vaccines. This combined vaccine may streamline immunization programs and enhance vaccination coverage. Full article