Background: Addressing Missed Opportunities for Vaccination (MOV) contributes to increased vaccination rates in children, reinforcing the need to investigate and intervene in the related factors. Objective: To analyze factors associated with missed opportunities for vaccination in children under one year of age in a Brazilian capital. Methods: This was a cross-sectional, analytical study conducted in seven Basic Health Units in Teresina, Piauí, Brazil. A previously validated questionnaire was applied to parents or guardians of a sample of 316 children. Data were collected from March to June 2025. Multivariable Logistic Regression was performed, and results were expressed as Odds Ratios. Results: Among the children, 53.5% had at least one MOV. The associated factors were: parents with two or more children (95% CI: 1.06–2.96), false contraindications (95% CI: 1.29–8.73), inadequate assessment of vaccination cards by health professionals (95% CI: 1.78–29.00), vaccine shortages in health units (95% CI: 1.57–18.28), and refusal to open multidose vaccine vials (95% CI: 1.81–19.31). Receiving information about vaccination in the previous month was a protective factor against MOV (95% CI: 0.25–0.77). The vaccines most frequently contributing to MOV were BCG (15.8%) and the COVID-19 vaccine, with 15.5% for the first dose and 14.9% for the second. Conclusions: The high prevalence of MOV found in this study indicates weaknesses in the immunization process and suggests the need for implementing measures to interrupt the chain of causes leading to MOV, thereby contributing to the achievement of the objectives of the Brazilian National Immunization Program.

Background/Objectives: Respiratory syncytial virus (RSV) is a major cause of acute respiratory infections and has long posed challenges to vaccine development because of historical safety concerns and the complexity of protective immunity. Recent advances in structural biology, maternal immunization, vaccines for older adults, and monoclonal antibodies have reshaped this field. This study aimed to analyze global research trends in RSV vaccine research using a bibliometric approach. Methods: A bibliometric study was conducted using records retrieved from the Web of Science Core Collection on April 1, 2026. Original articles and reviews published between 1968 and 2026 were selected through a title-based search strategy related to RSV and vaccination. Bibliometric indicators, citation patterns, collaboration networks, source distribution, and thematic structures were analyzed using Bibliometrix and Biblioshiny in R. Results: The final sample included 1,455 documents from 394 sources, with an annual growth rate of 8.7%. Scientific production increased markedly after 2010, with stronger acceleration after 2020. The United States led global output, followed by China, the United Kingdom, Canada, and the Netherlands. Vaccine was the most productive and locally influential source. Citation analysis identified the formalin-inactivated RSV vaccine studies from 1969 and the prefusion F protein study from 2013 as major intellectual milestones. Keyword analysis showed a shift from disease burden, epidemiology, and pathogenesis toward immunization, immunogenicity, maternal vaccination, older adults, and monoclonal antibodies. Conclusions: RSV vaccine research has evolved from a historically safety-constrained field to a mature translational area focused on prevention, implementation, real-world effectiveness, and equitable access.

Background/Objectives: Respiratory syncytial virus (RSV) is a major cause of acute respiratory infections and has long posed challenges to vaccine development due to historical safety concerns and the complexity of protective immunity. Recent advances in structural biology, maternal immunization, vaccines for older adults, and monoclonal antibodies have reshaped the field. This study aimed to analyze global research trends in RSV vaccine research using a bibliometric approach. Methods: A bibliometric study was conducted using records retrieved from the Web of Science Core Collection and Scopus on 1 September 2026. After database merging, deduplication, and data refinement, bibliometric indicators, citation patterns, collaboration networks, source distribution, and intellectual structure were analyzed using Bibliometrix and Biblioshiny in R. Results: The final corpus comprised 2516 documents published between 1968 and 2026 across 646 sources, with an annual growth rate of 10.7%. A total of 9298 authors were identified, with an average of 7.08 coauthors per document, and 24.56% of publications involved international collaboration. Scientific production increased markedly from the 2010s onward. The United States remained the leading contributor, while the most recent period showed broader participation from other countries. Vaccine was the most productive source. Citation analyses highlighted historical publications on the formalin-inactivated RSV vaccine and subsequent advances related to the prefusion F protein as important components of the field’s intellectual structure. Conclusions: RSV vaccine research has evolved from a historically safety-constrained field into a mature translational area focused on prevention, implementation, real-world effectiveness, and equitable access.

Background: Delayed and refused vaccination remain challenges to timely immunization during infancy and may involve different underlying factors. Objective: To analyze the factors associated with vaccination delay and refusal among children younger than 12 months. Methods: A household-based analytical cross-sectional study was conducted with 452 children in Teresina, Piauí, Brazil. Data were obtained through caregiver interviews and review of vaccination booklets. Vaccination delay and refusal were analyzed separately using Poisson regression with robust variance. Results: Vaccination delay occurred in 30.8% of children and was associated with age 7 to <12 months (aPR = 4.71), contraindication in cases of mild illness (aPR = 1.64), the caregiver’s decision not to vaccinate the child by the scheduled date (aPR = 1.79), and vaccine shortages (aPR = 1.84); satisfactory caregiver knowledge was inversely associated with delay (aPR = 0.58). Vaccination refusal occurred in 5.5% and was associated with age 7 to <12 months (aPR = 2.25), contraindication because of a previous reaction (aPR = 6.22), having considered no longer vaccinating the child after a previous reaction (aPR = 3.19), the caregiver’s decision not to vaccinate the child by the scheduled date (aPR = 3.08), and vaccine shortages (aPR = 2.31). Moderate and satisfactory knowledge were inversely associated with refusal (aPR = 0.32 and 0.13, respectively). Conclusions: Vaccination delay was more frequent than vaccination refusal. The outcomes shared some associated factors but also showed outcome-specific factors, supporting distinct approaches to improve vaccination timeliness and address refusal.