Search Results (294)

Objectives: This randomized, blinded, positive-controlled phase III clinical trial aims to evaluate the safety and immunogenicity of the Sabin strain-based inactivated polio vaccine (sIPV) produced by Biominhai in healthy infants after primary and booster immunization. Methods: A total of 1200 healthy infants, aged 2 months, were randomly assigned to two groups in a 1:1 ratio to receive either one dose of sIPV or the control wIPV at 2, 3, and 4 months of age, followed by a booster dose at 18 months. The safety and immunogenicity of both the primary and the booster immunization were assessed. Results: The incidence of adverse reactions (AEs) was significantly lower in the sIPV group compared to the wIPV group after the primary immunization. Specifically, redness was the most frequently reported AE, occurring in 9% of the sIPV group versus 14% in wIPV (p = 0.01). Diarrhea was also less common in the sIPV group (3%) compared to the wIPV group (8%, p = 0.0004). Moreover, there were no significant differences in incidence, severity, or symptoms of AEs between the groups after the booster immunization. Most AEs were classified as grade 1, and notably, no serious AEs (SAEs) were associated with the trial vaccine. Seroconversion rates for types 1, 2, and 3 poliovirus neutralizing antibodies, in the sIPV group, exceeded 98% at 30 days after primary immunization and remained above 90% at 30 days after booster immunization. Notably, seroconversion rates for all three serotypes following both primary and booster immunizations were non-inferior to those observed in the wIPV group. Additionally, the geometric mean titers (GMTs) of neutralizing antibodies against all types were significantly higher in the sIPV group. Conclusions: The sIPV produced by Biominhai demonstrated comparable safety and immunogenicity to the control vaccine after both primary and booster immunizations. Full article

Clusters of acute flaccid paralysis (AFP) caused by oral vaccine-derived poliovirus (VDPV) in 2022 and sporadic outbreaks in New York and Gaza highlight the ongoing risk of polio, alongside the persistent global threat posed by wild-type poliovirus. This study aims to develop and validate a quantitative reverse transcription PCR (RT-qPCR) panel that employs different primer–probe sets to simultaneously detect vaccine and wild-type poliovirus (WPV) in wastewater. Using an inactivated poliovirus vaccine (IPV) and engineered DNA fragments (eDNAf), the qPCR master mix (MM) performance, assay specificity, sensitivity (limit of detection, LOD), and recovery from IPV-spiked wastewater were evaluated. Compared with two-step RT-qPCR and qScript MM, one-step RT-qPCR with TaqMan MM improved sensitivity for the following polioviruses (PV): Sabin 1 in IPV and the eDNAf of Sabin 1, 2, and 3; WPV1 and WPV3; and poliovirus type 2 (any serotype 2). The LOD for Sabin 1 in IPV was 2.49 copies/PCR, while LODs for eDNAf of polio targets ranged from 1.06 to 3.12 copies/PCR. Sabin 1 recovery from IPV-spiked wastewater ranged from 10.26% to 57.27%. The RT-qPCR panel for poliovirus exhibited good specificity and sensitivity, with moderate viral recovery, enabling rapid implementation of wastewater monitoring for PV as needed. Full article

The aim of this research is to formulate and analyze a modified $S{I}_{p}IVR$ mathematical model to study the transmission dynamics of poliovirus and assess the impact of vaccination on disease control. The proposed model extends classical SEIV-type frameworks by incorporating a recovered compartment with long-term immunity and by replacing the traditional exposed class with a pre-infectious compartment ($I_p$) that captures silent viral shedding during the incubation phase of poliovirus. This modification addresses the critical epidemiological feature that individuals can transmit the virus before showing symptoms while maintaining biological accuracy in compartment definition. Several fundamental analytical properties are rigorously established, including positivity, boundedness, and the existence of a biologically meaningful invariant region. The basic reproduction number $R_0$ is derived using the next-generation matrix approach, and comprehensive stability analysis is carried out. The analysis shows that the DFE is locally and globally asymptotically stable whenever $R_0<1$. Using center manifold theory, a forward bifurcation is rigorously demonstrated, indicating that disease persistence emerges smoothly as $R_0$ crosses unity. Local and global sensitivity analyses of the basic reproduction number $R_0$ identify critical epidemiological parameters, and points to vaccination coverage and transmission rates as key drivers of outbreak dynamics. Numerical simulations confirm the analytical results and illustrates two different epidemiological scenarios, one with $R_0<1$, and another with $R_0>1$ along with neural network analysis by using the same data from both cases in a built-in function package in MATLAB-2020 software. It utilizes all of its hidden layers to check the data used by the model for validation performance and training and to find the absolute and mean squared errors. It also shows how vaccination suppresses the spread of infection. These findings provide a strong mathematical basis for public health policy, offering strategic insight into how vaccination campaigns might be optimized to accelerate progress toward global polio eradication. Full article

Poliovirus (PV), a historically significant enterovirus responsible for severe paralytic diseases, has seen its incidence dramatically reduced through widespread vaccination efforts, propelling global eradication initiatives. Despite the success of traditional oral poliovirus vaccines (OPVs) and inactivated poliovirus vaccines (IPVs), challenges such as vaccine-derived virus reversion and biosafety concerns during vaccine production persist. Virus-like particle (VLP) vaccines, which mimic native viral structures without containing viral genomes, offer enhanced safety profiles and robust immunogenicity, positioning them as promising candidates for next-generation poliovirus vaccines, especially in the post-certification era. This review systematically summarizes current progress in poliovirus VLP vaccine research, including the diverse expression systems employed for VLP production, strategies for peptide assembly and stabilization, and evaluations of antigenicity and immunogenicity. Additionally, it highlights structural analyses utilizing cutting-edge cryo-electron microscopy. By integrating recent developments in genetic engineering, structural biology, and immunology, this article discusses the advantages and challenges associated with poliovirus VLP vaccines and explores future directions aimed at supporting the global goal of a poliovirus-free world. This comprehensive overview aims to provide a theoretical foundation and technical guidance to facilitate the development and deployment of safer and more effective poliovirus vaccines. Full article

Background: We aimed to evaluate the impact of a Private Provider Engagement (PPE) model that integrated neighborhood private health providers into the immunization system to improve vaccine uptake and reduce coverage disparities among marginalized communities in Karachi, Pakistan, where health inequities and the risk of vaccine-preventable diseases remain high. Methods: Routine immunization service corners were established at nine private clinics in urban settlements of eight high-risk union councils (HRUCs) in Karachi. A quasi-experimental before-and-after study design was used with a baseline survey conducted in May–July 2022 and an end-line survey in April–June 2024. Households were selected using a multistage cluster sampling approach, and data were collected from parents or primary caregivers of children aged 4–11 months residing in the catchment areas for >3 months, using an adapted WHO immunization coverage questionnaire. The primary outcome was child immunization status for BCG, Polio, Pentavalent (DTP-3), Rotavirus, PCV, TCV, and MR vaccines, categorized as fully vaccinated, partially vaccinated, or unvaccinated, and verified through vaccination cards or caregiver recall. Multinomial and binary logistic regression were used to investigate factors associated with immunization coverage. Results: A total of 2167 children were surveyed (1141 children at baseline; 1026 children at end-line). The proportion of fully immunized children more than doubled across sexes, with significantly higher adjusted odds at endline (aOR: 6.34, 95%CI: 2.45–16.21). Age-appropriate uptake of all antigens improved, with over fourfold odds for receiving the Penta-3 vaccine (aOR 4.55, 95%CI: 3.55–5.82) and more than threefold odds for receiving the MR-1 Vaccine (aOR 3.67, 95%CI: 2.37–5.67). Parental education strongly predicted immunization, with the highest odds among children of fathers with secondary or higher education or skilled labor. Fully immunized Pashto-speaking children increased at endline but had the lowest odds compared to Urdu-speaking children. Conclusion: The PPE model increased vaccination coverage and reduced disparities in Karachi’s urban settlements, demonstrating potential for scale-up to strengthen routine immunization and reduce the number of zero-dose children. Full article

Background: Large urban centers in low- and middle-income countries (LMICs) often have persistent pockets of under-immunized children, despite higher overall vaccination coverage than rural areas. Lahore, a megacity in Pakistan, had the lowest rate of fully immunized children in Punjab province as of 2022 (70%), partly due to challenges in its urban slums. In 2023, an innovative intervention was implemented, utilizing Pakistan’s extensive polio eradication workforce to identify and reach children who were missing routine vaccinations. Objective: The objective was to assess changes in routine immunization coverage during a pre–post evaluation period in which polio campaign workers were engaged to support routine immunization among under-immunized urban populations in Lahore. Methods: A special outreach strategy engaged polio vaccination teams to conduct door-to-door visits of children aged 12–23 months, recording each child’s routine immunization status. These data were integrated into the electronic health system and provided to Expanded Programme on Immunization (EPI) staff for targeted follow-up. Two cross-sectional household surveys of caregivers of children aged 12–23 months were conducted: a 2022 baseline survey and a 2023 follow-up survey conducted six months after implementation. Both surveys used two-stage cluster sampling and WHO-standard immunization coverage methods, with vaccination status verified using cards or caregiver recall. Results: A total of 773 children were surveyed at baseline and 780 at endline. Full immunization coverage increased from 69.8% (CI: 64.13–74.98) to 85.1% (CI: 81.01–88.51). Partial immunization declined from 26.9% (CI: 22.37–31.92) to 14.5% (CI: 11.27–18.50), and the proportion of children not vaccinated at all dropped from 3.3% (CI: 1.92–5.60) to 0.3% (CI: 0.11–0.98). Penta-3 coverage improved from 83.2% (CI: 78.65–87.04) to 94.1% (CI: 91.15–96.07), and Measles 1 from 76.9% (CI: 71.80–81.40) % to 92.1% (CI: 88.71–94.56). Immunization card retention increased from 69.9% (CI: 64.15–75.16) to 84% (CI:81.19–86.94). Improvements were observed across all socio-demographic groups, with a higher impact in peri-urban clusters and low socio-economic groups, and all remained statistically significant. Conclusions: Our findings showed improvements in routine immunization coverage in urban Lahore between 2022 and 2023. This period coincided with district-wide implementation of a polio worker outreach strategy as well as the broader post-COVID-19 recovery of immunization services. This study lacked a control group; therefore, the findings indicate a temporal association occurring during the post COVID-19 recovery period, rather than definitive evidence of causal impact. Nonetheless, integrating the workforce of the polio program into routine immunization could be a promising programmatic strategy to close immunization gaps in urban areas. Full article

Background: The COVID-19 pandemic significantly disrupted health systems, including the delivery of childhood immunizations. This study assessed COVID-19 vaccination coverage in families of children with incomplete routine immunization and explored why adults accepted COVID-19 vaccines despite skipping routine vaccination for their children in the district of Swat, Khyber Pakhtunkhwa, Pakistan. Methods: A mixed-methods study was conducted in Swat District during March 2022–April 2023. A cross-sectional survey assessed COVID-19 vaccination in household members of children under 2 years of age for whom vaccination registries showed missed routine vaccinations. In-depth interviews with 18 household members explored motivations for vaccine acceptance through thematic analysis. Results: Among 249 families of children with incomplete immunization found through vaccination records, 237 families (88% response) were interviewed. Among 382 children below 2 years of age in these families, 29.5% (n = 113) were fully vaccinated, 67.5% (n = 258) were incompletely vaccinated according to age, and 2.9% (n = 11) had not received any vaccine. Data from 237 of the defaulter children—one per household—was included in further analysis. Among household members above 12 years of age, 87% (964/1103) of males and 82% (n = 901/1093) of females were vaccinated against COVID-19. Households with at least one fully vaccinated child were significantly more likely to have vaccinated family members. Multivariable analysis showed maternal COVID-19 vaccination (AOR 2.08, 95% CI: 1.15–3.76) and urban residence (AOR 2.08, 95% CI: 1.14–3.79) were associated with full childhood vaccination. In-depth interviews revealed that key motivators for COVID-19 vaccination included the perception that it was mandatory, house-to-house vaccination, and fear of hospitalization or death. Conclusions: Vaccine requirements and ease of access to vaccination services enhanced coverage with COVID-19 vaccines among families of children with incomplete routine immunization. Ethical use of vaccine requirements and community education to enhance levels of risk perception of vaccine-preventable diseases could potentially improve childhood immunization. Full article

Coxsackievirus A16 (CVA16), a major etiological agent of hand, foot, and mouth disease, is increasingly contributing to neurological complications, with no vaccines or virus-specific antivirals currently available. To identify CVA16-restricting host factors, we investigated the role of the interferon-stimulated gene shiftless (SHFL), previously implicated in the control of other RNA viruses. Using CRISPR–Cas 9, we generated SHFL knockout rhabdomyosarcoma cells and assessed viral replication, cytopathic effects, and replication stage dynamics. We evaluated disease progression and tissue injury in neonatal mice infected with a mouse-adapted CVA16 strain. SHFL expression was strongly induced during CVA16 infection and was inducible by exogenous interferon-β treatment, and its loss markedly increased infectious virus production, accelerated early replication, and exerted severe cytopathic effects. In vivo, SHFL deficiency led to rapid weight loss, pronounced neurological signs, increased viral burden across multiple tissues, and uniform mortality, together with high viral loads and extensive pathological damage in the central nervous system, lungs, and skeletal muscle. Transcriptomic analyses revealed SHFL-dependent modulation of adhesion- and mitogen-activated protein kinase-related pathways. Overall, our results suggest SHFL as a key determinant of host resistance to CVA16, acting mainly at the post-transcriptional stage to limit viral spread and tissue injury, and highlight SHFL-linked pathways as promising host-directed antiviral targets. Full article

Enteroviruses (EVs) are small, non-enveloped RNA viruses that can cause diverse clinical outcomes, particularly severe in patients with primary immunodeficiency (PID) due to their impaired ability to clear infections. This study aimed to characterize EV excretion among 138 Tunisian PID patients over a five-year period, to identify circulating EV serotypes and assess their genetic diversity. A total of 558 stool samples were collected and analyzed by virus isolation and intratypic differentiation using RT-qPCR. Molecular typing was performed through Sanger sequencing of the VP1 region and whole genome sequencing using Next-Generation Sequencing (NGS) technologies. Phylogenetic analysis was conducted using the Maximum Likelihood (ML) method. EVs were detected in 55 stool samples from 23 patients. The excretion kinetics of EVs ranged between 30 and 946 days. Thirteen serotypes were identified, including one Poliovirus (PV) and twelve Non-Polio Enteroviruses (NPEVs), predominantly belonging to species B. Two previously unreported serotypes in Tunisia were detected: Coxsackievirus A5 (CVA5) and Echovirus type 19 (E19). In addition, five patients presented enhanced susceptibility to the excretion of successive EV serotypes, and one patient exhibited a co-infection. A possible recombination event was identified in one patient involving Coxsackievirus B5 (CVB5), Coxsackievirus A9 (CVA9) and Coxsackievirus B1 (CVB1) sequences. Phylogenetic analysis showed close genetic relationships with European, American and Asian strains. These findings underscore the dynamic nature of EV circulation and the importance of ongoing molecular surveillance to detect emerging serotypes and guide public health strategies. Full article

Human non-polio enteroviruses (NPEVs) cause a plethora of infections in humans, ranging from mild to severe neurological diseases including aseptic meningitis. NPEVs are the leading cause of aseptic meningitis in both children and adults worldwide. In Russia, reports of NPEV infections have surged, especially in the post-COVID era starting in 2022, with elevated infection rates into 2023. A comprehensive examination of the whole genome is crucial for understanding the evolution of NPEV genes and for predicting potential outbreaks. This study focused on identifying the circulating NPEV strains in the Ural Federal District and Western Siberia, using Sanger sequencing and next-generation sequencing (NGS) methodologies. Biological samples were collected from (n = 225) patients diagnosed with aseptic meningitis. Bioinformatics analysis targeted the nucleotide sequences of the major capsid protein (partial VP1) gene fragment, and the assembly of whole NPEV genomes. A total of 159 NPEVs were characterized, representing 70.7% of the collected samples. The main capsid variants forming the predominant genotypic profile included E30 (n = 39, 24.3%), E6 (n = 31, 19.3%), and CVA9 (n = 25, 15.6%). Using NGS, we successfully assembled 13 whole genomes for E6, E30, EV-B80, CVA9, CVB5, E11, and EV-A71 and 3 partial genomes for E6 and EV-B87. This molecular-genetic analysis provides contemporary insights into the genotypic composition, circulation patterns, and evolutionary dynamics of the dominant NPEV associated with aseptic meningitis in the Ural Federal District and Western Siberia. The laboratory-based monitoring and epidemiological surveillance for genetic changes and evolutionary studies are important for improving prevention and healthcare. Full article

Background/Objectives: Despite large-scale measles and rubella (MR) vaccination campaigns in West Africa, measles outbreaks persist, raising concerns about campaign effectiveness, coverage, and underlying determinants. This study assesses the impact of MR follow-up campaigns in 12 of 17 West African countries (2024–2025) and examines the factors contributing to post-campaign outbreaks. The main objective of this study is to evaluate the impact of MR campaigns on measles transmission, identify the characteristics of post-campaign outbreaks, and propose strategies to improve campaign effectiveness and accelerate progress toward measles elimination in West Africa. Methods: We conducted a cross-sectional and ecological analytical study to examine spatial and temporal variations based on measles surveillance data from 2024 to 2025, post-campaign coverage surveys (PCCS), district-level outbreak reports, and administrative coverage reports. Trends in measles cases before and after the MMR campaigns were assessed, along with demographic characteristics and spatial analyses of confirmed cases. Results: In 2024, 70.5% (12/17) of countries conducted measles vaccination campaigns, but measles outbreaks increased in 2025 (64 districts in 2024 versus 383 in 2025). Children under five remained the most affected (54%), with 85% of cases being either unvaccinated (57%) or of unknown status (28%). Administrative coverage exceeded 95% in most countries, but measles PCCS revealed gaps, with only Senegal (93%) and Guinea-Bissau (94%) achieving high verified coverage. No country achieved 95% national MPCC. Conclusions: Suboptimal campaign quality, gaps in immunity beyond target age groups, and unreliable administrative data contributed to the persistence of outbreaks. Recommendations include extending Measles vaccination campaigns to older children (5–14 years), improving preparedness by drawing on experiences from other programs such as polio, standardizing PCCS data survey and analysis methodologies across all countries, and integrating Measles vaccination campaigns with other services such as nutrition. Full article

Background/Objectives: Vaccination programs are highly effective public health interventions, yet parental hesitancy toward combination vaccines has led to growing demand for alternative vaccination schedules, defined in this study as parental requests to split or replace recommended combination vaccines with single-antigen vaccines for non-clinical reasons. While parental attitudes have been widely studied, little empirical evidence exists on the real-world use of single-antigen vaccines and their public health implications in countries with otherwise high coverage. This study examined the prevalence patterns and parental motivations for requesting such alternative vaccination schedules in Israel, where national guidelines recommend specific combination vaccines, including measles-mumps-rubella-varicella (MMRV) and the pentavalent diphtheria-tetanus-pertussis–inactivated polio–Haemophilus influenzae type b (DTaP+IPV+Hib) vaccines, but informal accommodations exist. Methods: A mixed-methods design was employed: a retrospective cohort analysis of vaccination data from 2018 to 2021 (before and during the COVID-19 pandemic) focused on measles (first dose at 12 months) and pertussis (four-dose primary series), followed by semi-structured interviews with Maternal and Child Health clinic providers, policymakers, and parents. Results: Alternative vaccination schedules involving single-antigen measles or pertussis vaccines are occasionally used despite official policy, accounting for less than 1% of vaccinations overall. Outcomes include delayed administration, lower uptake of combination vaccines, and incomplete protection in certain groups. Parents cited safety concerns, fear of immune overload, and mistrust of authorities. These concerns were often amplified by misinformation, while providers described balancing parental preferences with the need for adequate coverage. Conclusions: This study provides new evidence on how vaccine hesitancy translates into service utilization, highlights the tension between individualized parental decision-making and contribution to collective health, and underscores the need for communication, policy strategies and service designs that sustain high coverage while addressing community-specific concerns. Full article

Background: Women’s empowerment has been significantly associated with improved child health outcomes. Cambodia, amid a rapid socioeconomic transition, offers a critical setting to examine how advancements in women’s empowerment over the past decade have influenced child immunization completion within the first two years of life. Methods: Data from the Cambodia Demographic and Health Surveys conducted in 2010, 2014, and 2021–22, encompassing 9222 women with recent births, were analyzed. Empowerment was measured across literacy and information access, employment, and decision-making domains. Multinomial logistic regression assessed associations between empowerment factors and completion of oral polio (OPV), diphtheria–tetanus–pertussis (DTP), pneumococcal conjugate (PCV), and measles–rubella (MR) vaccines, adjusting for demographic and socioeconomic variables. Results: Between 2010 and 2022, women’s empowerment in Cambodia improved significantly, marked by higher literacy rates, nearly half of women completing primary education, and expanded digital access, with 82.4% owning mobile phones and approximately 50% using the internet daily. While non-working women slightly increased, agricultural employment declined by 20%, and cash earnings rose from 48.7% to 82.5%. Most women participated in major household decision-making, either independently or jointly. Completion rates for OPV, DTP, and PCV ranged from 79% to 83%, while just over half of children were fully vaccinated against measles. Higher maternal education and cash earnings were positively associated with OPV, DTP, and PCV completion but negatively associated with measles vaccination. Women in agricultural work were less likely to complete measles vaccination for their children than non-working women. Joint decision-making regarding the use of respondents’ income was associated with a higher likelihood of measles non-completion (OR = 2.26, 95% CI: 1.13–4.51), whereas joint decision-making about respondents’ health care was associated with a higher likelihood of measles completion (OR = 0.42, 95% CI: 0.21–0.83). Conclusions: Women’s empowerment remains a key determinant of vaccination outcomes in Cambodia. The distinct pattern observed for measles suggests that vaccines scheduled for older ages encounter greater structural and behavioral barriers. To overcome these challenges, strategies should focus on enhancing defaulter tracking, implementing reminder systems, expanding outreach and catch-up programs, and improving the convenience of vaccination services. Full article

Objective: To explore the problems with non-National Immunization Program vaccinations in Hubei Province and to provide the basis for follow-up vaccination and management. Methods: Vaccination data on non-NIP/NIP vaccine doses were extracted from the Hubei Provincial Immunization Planning Information Management System. Descriptive epidemiological analyses were conducted to examine dose administration, vaccine-type composition, regional distribution, and substitution patterns. The trend χ² test was used to assess temporal significance. Multistage regression analysis was performed using Joinpoint software. Results: From 2011 to 2024, a total of 91,009,259 doses (annual average: 6,500,661) with 35 types of non-NIP vaccines were administered in Hubei Province, China. The top five vaccines by doses administered were influenza vaccine, rabies vaccine, Hemophilus influenzae type b conjugate vaccine, varicella attenuated live vaccine, and enterovirus 71 inactivated vaccine. Before 2024 (2011–2023), vaccine utilization showed a long-term upward trend: per 10,000, population usage rose from 657.07 (2011) to a peak of 2393.21 (2023) (Increase: 264.22%, χ² = 138.62, p < 0.05) (AAPC = 10.92%, p < 0.05) and non-NIP’s share of total vaccines increased from 25.52% (2011) to 65.95% (2023), (Increase: 154.33%, χ² = 89.47, p < 0.05) (AAPC = 8.74%, p < 0.05). A notable reversal occurred in 2024. Non-NIP doses dropped from 13,971,544 (2023) to 10,238,861 (2024) with population usage falling from 2393.21 (2023) to 1755.03 (2024) (decrease: 26.66%) per 10,000, with the top three declines being in inactivated polio vaccine (IPV) (decrease: 49.53%), influenza vaccine (decrease: 44.21%), and oral rotavirus attenuated live vaccine (decrease: 43.50%). The total number of substitutive non-National Immunization Program (non-NIP) vaccine doses administered reached 16,618,755, with an overall substitution rate of 10.10%. This rate showed a steady upward trend from 5.57% in 2011 to 24.74% in 2023 (trend χ² = 15.11, p < 0.05), yet it increased to 28.03% in 2024. Conclusions: Non-NIP vaccines and NIP-substitute use grew steadily for over a decade, then contracted sharply in 2024. Decision-makers should investigate the sudden dip, differentiate discretionary from replacement demand, and reallocate funds to sustain equity and prevent further erosion of coverage. Full article

Background: Childhood immunization is one of the most effective public health strategies for reducing morbidity and mortality from vaccine-preventable diseases. Although overall vaccination coverage in the United States remains high, disparities persist across socioeconomic and healthcare access groups. Understanding these disparities is particularly important in the post-COVID-19 era, when increased vaccine hesitancy may threaten progress in maintaining equitable coverage. Materials and Methods: We analyzed data from the National Immunization Survey–Child (NIS-Child), focusing on U.S. children aged 19–35 months in 2023, corresponding to cohorts reaching this age during or after the COVID-19 pandemic. The primary outcome was receipt of the up-to-date combined 7-vaccine series (4:3:1:3:3:1:3: ≥4 doses of DTaP, ≥3 doses of polio, ≥1 dose of measles-containing vaccine, full Hib series, ≥3 doses of hepatitis B, ≥1 dose of varicella, and ≥3 doses of PCV). Logistic regression models were used to estimate associations between vaccination coverage and key explanatory variables: household income-to-poverty ratio, maternal education, health insurance type, and provider facility type, controlling for demographic and regional covariates. Disparities were quantified using concentration indices (CIs). Results: Among children in the analytic sample, overall coverage for the 7-vaccine series was only 78.5%. Nonetheless, disparities were evident. Children from households with lower income-to-poverty ratios (<1 × FPL: OR = 0.44, 95% CI = 0.37–0.53; 100–200%: OR = 0.66, 95% CI = 0.56–0.79), those covered by Medicaid (OR = 0.54, 95% CI = 0.45–0.64), other insurance (OR = 0.48, 95% CI = 0.37–0.61), or uninsured (OR = 0.27, 95% CI = 0.18–0.42), and those whose mothers had lower educational attainment (<12 years: OR = 0.35, 95% CI = 0.28–0.44) had significantly lower odds of being up-to-date. Similar associations were observed across specific vaccines. Unadjusted CIs for income-to-poverty ratio (0.04, p < 0.01), maternal education (0.04, p < 0.01), health insurance (0.03, p < 0.01), and provider type (0.03, p < 0.01) decreased but remained statistically significant after adjustment (0.02, 0.02, 0.01, and 0.02, respectively; all p < 0.01). No significant disparities were found by census region or race/ethnicity. Discussion: Despite relatively high overall vaccination coverage among U.S. children born during and after the COVID-19 pandemic, disparities by socioeconomic and healthcare access factors persisted. However, the absolute magnitude of these disparities was very small (concentration indices ≤ 0.04). These findings suggest that while inequities remain statistically measurable, their scale is limited in absolute terms. Targeted efforts to address income, insurance, maternal education, and provider-related barriers will be important to sustain equitable immunization coverage in the post-pandemic era. Full article