Incomplete Vaccination Schedule Research Articles

Zero-dose children in Latin America: analysis of the problem and possible solutions

Introduction Zero-dose children (ZDC) are defined as those that have never been reached by routine immunization services. In Latin America, almost 2.7 million infants younger than 1 year of age, have incomplete vaccination schedules, and vaccine preventable diseases such as measles or polio have increase worldwide. ZDC are reported to reside in high risk and fragile settings, including remote-rural areas, urban slums, and conflict-affected areas. Identifying the problem and settings in each country is mandatory to propose possible solutions to the immunization coverage situation. Areas covered In November 2023, a group of experts of the Latin America Society of Pediatric Infectious Diseases (SLIPE) analyzed the global and regional reality of ZDC, and present in this document an updated reality of the Latin American region and the weight of the possible interventions to overcome this problem. Expert commentary Communication is a key element to improve vaccination coverage, as it is quality and use of vaccination data. Campaigns that deliver targeted and effective messages to communities and families, provide education about vaccination, avoid missed vaccination opportunities, and coordinate efforts across different sectors and communities, among other strategies, could improve the current immunization situation.

Hepatitis B Status in Hemodialysis Patients: An Overview from Morocco

Background: Patients with end-stage renal disease, particularly hemodialysis patients are at risk for contracting hepatitis B virus (HBV) because of their compromised immune status and exposure to blood products. Regardless of a shorten in the incidence of HBV infection, surveillance is mandatory in preventing the spread of this dreaded virus. Infection control practices, regular review of serologic markers and hepatitis B vaccination are the cornerstone to maintain a safe environment for dialysis. The aim of our study is to provide an overview of the serologic and vaccination status for hepatitis B in hemodialysis patients. Methods: A cross-sectional study was carried out in our hospital haemodialysis center to evaluate hepatitis B serological status and vaccination profile of chronic kidney disease patients on chronic dialysis program in Agadir, Morocco. Serologic profile results were checked for all patients (anti-HBc, HBsAg and anti-HBs). Individuals without previous vaccination, incomplete vaccination schedule or no serological conversion (anti-HBs <10mUI/ml) have been prescribed hepatitis B vaccine as it is still not available in public health center in Morocco, with a monitoring of adverse events. Results: Fifty-five dialysis patients were included in the study. The majority were male (56,4%), mean age was 59.29 years. All patients were already screened and negative for HBsAg. 69,09% of the population study were vaccinated against hepatitis B (65,78% complete and 34,22% incomplete schedule), with a seroconversion rate of 78,94%. A booster dose of vaccine was given to patients who had not achieve seroconversion (anti HBs <10mUI/ml), because of the immunocompromised state of the dialysis patient. All patients were already screened for anti-HBc. 20% of them were positive, indicating previous contact with the virus. This contact was immunizing in 80 % of patients (anti-HBs>10mUI/ml). For the two patients whose previous contact was not immunizing, the HBV vaccine

Incomplete vaccination in children under 2 years of age at the Tulcán Sur Health Center

Vaccination campaigns are carried out worldwide with a process of great importance in disease prevention. Within the population, children under two years of age are a priority and are part of the first vaccination schedules that are developed. The research analyzed the situation of the children of Tulcán Sur in 198 families. To obtain results, theoretical and empirical methods were used, where the application of a survey made it possible to obtain various data of interest for the analysis. The results show the existence of a low education even on the knowledge and mastery of the importance of vaccines, which together with the economic situations and remoteness in several cases, cause an incomplete vaccination schedule in a significant number of children under two years. This situation shows the need to achieve broader and more systematic work by health personnel on the population in order to achieve greater participation in vaccination processes with emphasis on children under two years of age. The lack of knowledge on the part of the population about vaccines and the still existence of myths that reduce the credibility of vaccination and undermine the process and its effectiveness in preventing diseases are evident

Possíveis causas e consequências da baixa cobertura vacinal de sarampo: um estudo de revisão integrativa da literatura

Measles is a viral, infectious, preventable disease that requires high vaccination coverage in order for herd immunity to be achieved and for outbreaks to be prevented. This study aims to identify the possible causes and consequences of low measles vaccination coverage. This is an integrative literature review based on original articles published in electronic databases between 2015 and 2021. Said articles were identified through controlled descriptors, prepared for structural and methodological evaluation, and categorized using the thematic content analysis technique. After application of the inclusion, exclusion and checklist criteria, six publications remained. Two thematic categories were defined: “Possible causes of low measles vaccination coverage worldwide” and “Consequences of low measles vaccination coverage”. Evidenced causes included: absent, incomplete or late vaccination schedule, late implementation of mass vaccination, insufficient stock of vaccines, and increased hesitation on the part of parents. The consequences were an increase in measles cases,in the risk of mortality, and in the health expenses of the public sector. It was concluded that a reduction in measles vaccination coverage has the potential to impact the population’s health conditions,to raise morbimortality indicators andto cause losses to public coffers.

Clinical and thyroid profile in patients with COVID-19 hospitalized in an intensive care unit.

This study aimed to summarize the epidemiological and clinical features of thyroid function in COVID-19 patients in the intensive care unit (ICU) of Civil Fray Antonio Alcalde Hospital in Mexico. This is a cross-sectional study that included 63 ICU patients with COVID-19 from August 2021 to December 2021. Thyroid function was evaluated through the TSH, T4, T3, and FT3 measures. Comorbidities such as diabetes mellitus type 2 (T2DM), arterial hypertension (HT), body mass index (BMI), and biochemical biomarkers, including procalcitonin (PCT) and C reactive protein (CRP), were also analyzed. A total of 63 patients with COVID-19 were hospitalized in the ICU; 42 (67%) were male, and 21 (33%) were female, with a mean age of 47 (range of 26-76 years). A total of 49 (78%) patients were non-vaccinated, 5 (8%) had an incomplete vaccination schedule, and 4 (6%) had completed the vaccination schedule. Regarding BMI, 10 (16%) were overweight, and 26 (40%) reported obesity. When assessing thyroid function, 8 (13%) patients were euthyroid, and 55 (87%) showed alterations on the thyroid hormonal axis, mainly a low concentration of TSH (0.56±0.79; p=0.0001) and FT3 (2.34±0.52; p=0.0006). In addition, increased PCT concentrations were associated with a higher risk to decease (1.22 vs. 8.21; p=0.0001) in this group of patients. Based on our findings, it appears that COVID-19 patients with low TSH and FT3 levels, who have not been vaccinated against SARS-CoV-2, are overweight or obese, and exhibit high levels of PCT are more likely to experience a poor prognosis and even mortality.

Predictors of incomplete COVID-19 vaccine schedule among adults in Scotland: Two retrospective cohort analyses of the primary schedule and third dose

BackgroundVaccination continues to be the key public health measure for preventing severe COVID-19 outcomes. Certain groups may be at higher risk of incomplete vaccine schedule, which may leave them vulnerable to COVID-19 hospitalisation and death. AimTo identify the sociodemographic and clinical predictors for not receiving a scheduled COVID-19 vaccine after previously receiving one. MethodsWe conducted two retrospective cohort studies with ≥3.7 million adults aged ≥18 years in Scotland. Multivariable logistic regression was used to estimate adjusted odds ratios (aOR) of not receiving a second, and separately a third dose between December 2020 and May 2022. Independent variables included sociodemographic and clinical factors. ResultsOf 3,826,797 people in the study population who received one dose, 3,732,596 (97.5%) received two doses, and 3,263,153 (86.5%) received all doses available during the study period.The most strongly associated predictors for not receiving the second dose were: being aged 18–29 (reference: 50–59 years; aOR:4.26; 95% confidence interval (CI):4.14–4.37); hospitalisation due to a potential vaccine related adverse event of special interest (AESI) (reference: not having a potential AESI, aOR:3.78; 95%CI: 3.29–4.35); and living in the most deprived quintile (reference: least deprived quintile, aOR:3.24; 95%CI: 3.16–3.32).The most strongly associated predictors for not receiving the third dose were: being 18–29 (reference: 50–59 years aOR:4.44; 95%CI: 4.38–4.49), living in the most deprived quintile (reference: least deprived quintile aOR:2.56; 95%CI: 2.53–2.59), and Black, Caribbean, or African ethnicity (reference: White ethnicity aOR:2.38; 95%CI: 2.30–2.46).Pregnancy, previous vaccination with mRNA-1273, smoking history, individual and household severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) positivity, and having an unvaccinated adult in the household were also associated with incomplete vaccine schedule. ConclusionWe observed several risk factors that predict incomplete COVID-19 vaccination schedule. Vaccination programmes must take immediate action to ensure maximum uptake, particularly for populations vulnerable to severe COVID-19 outcomes.

Non-compliance causes with the vaccination schedule in children under 5 years of age

Background: The immunization is a very important process for the organism of the human body, since in this process the body becomes resistant to various pathologies caused by viruses and bacteria. Vaccines are administered from the first days of life to acquire defenses in the body and fight diseases successfully. Objective: Analyze the causes of non-compliance with the vaccination schedule of children under 5 years in San Bartolomé de Pinllo. Methods: A quantitative approach of descriptive scope of cross-sectional design was used, with a sample of 45 parents or caretakers of children. A questionnaire consisting of 15 questions was used with a Cronbach's alpha reliability of 0.99%. Results: The incomplete vaccination schedule in children under 5 years in San Bartolomé de Pinllo was determined due to sociodemographic, institutional, and cognitive causes. Conclusions: This investigation allowed us to determine the percentage of children under 5 years who have an incomplete vaccination schedule and the reasons for non-compliance. However, it is necessary to provide information to the children's caretakers about the importance of vaccinations.

Intimate Partner Violence and Early Childhood DevelopmentViolência por parceiro íntimo e desenvolvimento na primeira infância

To describe the prevalence of different types of intimate partner violence and estimate how this relates to child development in a low-income country in Latin America. The relationship between intimate partner violence and childcare practices, including the use of physical punishment, was also examined. An observational study was conducted using data collected as a baseline for an impact evaluation of the National Early Childhood Program in Nicaragua between 2013 and 2014. The sample included 8921 children between 0 and 5 years and 7436 mothers or caregivers in municipalities with an extreme poverty rate of over 0.2. The data revealed that 61% of mothers or caregivers reported controlling behavior by their partners, 50% suffered emotional violence, and 26% suffered physical violence at some point in their lives. Furthermore, the data demonstrated that children exposed to intimate partner violence displayed greater behavioral problems and delayed language and social-emotional development. These children are also more likely to be born prematurely and to have incomplete vaccination schedules. Finally, homes exposed to intimate partner violence are more likely to create more hostile and unsafe environments for children. The results reflect the magnitude of intimate partner violence and its detrimental effects on children. Public policies need to be devised and implemented not only to prevent this behavior and mitigate sequelae in exposed children but also to curb the intergenerational transmission of violence.

Evolución de los pacientes tratados en el área de COVID-19 severa de un hospital público según estado de vacunación. Estudio de vida real

Mass vaccination with the different anti SARS-CoV-2 compounds is so far the best tool to overcome the global health crisis. However, despite having different documents that support the efficacy of vaccines, a good part of the population remains reticent or fearful. The present study seeks to demonstrate the usefulness of vaccines with simple local data arising from our real-life experience. The evolution of 97 patients admitted to the severe COVID area of a public regional reference hospital in the south of the Province of Mendoza, Argentina, according to their vaccination status at admission, is described. All patients received the treatment suggested by the current guidelines of the Ministry of Health. 60.82% of hospitalized patients had an incomplete vaccination schedule (< 2 doses) and their mortality rate was higher than that of patients with 2 or more doses of anti-COVID vaccines (30.50% vs 21.05%). The differences observed were more marked when the groups of patients younger than 60 years were comparatively analyzed. The observations described in our work support the usefulness of SARS-CoV-2 vaccines, regardless of their origin, with patients in whom various risk factors coexist and outside of a clinical trial laboratory.

No cumplimiento del esquema de vacunación nacional en niños menores de 5 años en la selva peruana en el año 2019

In the past decade, levels of coverage on children vaccination had been decreasing nationwide, even more in the Peruvian jungle, reason why is an important public health’s subject to attend. The purpose of this investigation was to analyze maternal and social factors that are associated with incomplete vaccination schedules on children under 5 years old on the Peruvian jungle. It is an observational, analytic investigation, using a secondary source from the Demographic and Family survey (ENDES) from 2019, where is found the information of all the under 5 years old with the healthcare card of oral information given by the mother. Then after selecting the chosen variables, we used the SPSS statistic program for the posterior analysis. Of the 4373 surveys studied; it was shown that 57.5% of children under 5 years have the incomplete vaccination schedule. The multivariate analysis found that non-compliance with the vaccination schedule associated with maternal and social factors such as not having health insurance (ORa 1.72; p<0.01, IC95% 1.39-2,13), poverty (ORa-1,427, p<0.01, IC95% 1.89-1.71), native mother tongue (ORa-1.50, p<0.01, IC-1.13-2,0), problems attending the health center (ORa-1,213, p=0.02, IC95% 1.02-1.44), live outside the city (ORa-1.31, p<0.01, IC95% 1.09- 1.58), age under the age of 24 as a mother/guardian (ORa-1.38, p<0.01, IC95% 1,186-1,619). Not having health insurance, living in poverty, having trouble going to the health center, living outside the city, having a different mother tongue than Spanish and age under 24 are factors associated with non-compliance with the vaccination schedule.

SARS-CoV-2 Infection Evolution Among Nephrologists During the Pandemic: Clinical Features and Impact of Vaccination

SARS-CoV-2 Infection Evolution Among Nephrologists During the Pandemic: Clinical Features and Impact of Vaccination

Desnutrición crónica en niños menores de cinco años de la comunidad indígena awá, Barbacoas (Nariño, Colombia), 2019

Introduction: Chronic malnutrition in children under 5 years old is defined as stunting due to recurrentnutritional deficiencies associated with poverty, maternal health, and nutrition. This study aimed to identify the prevalence of chronic malnutrition and associated factors in children under 5 years old from the indigenous Awá community, at Barbacoas, Nariño in 2019. Materials and methods: A cross-sectional study was conducted, which included 527 children under 5 years old from the Awá community who attended a health institution for growth and development program. Chronic malnutrition was evaluated as an outcome, whereas sociodemographic, nutritional and other health characteristics as associated factors. Chi-square, Fisher’s exact, and Mann–Whitney’s U test were used to determine statistical association. Additionally, the relationship was adjusted through a multiple logistic regression model. Results: Chronic malnutrition was found in 17.6% of children. The statistical association was found in children of the adolescent mother, incomplete vaccination schedule, and age and birth weight. Conclusion: In children under 5 years old in the Awá community, the frequency of chronic malnutrition is above the average for the general population in Colombia. Prioritizing the active search for chronic malnutrition in children whose mothers are adolescents and those with low birth weight and incomplete vaccination is important.

Factors associated with the incomplete opportune vaccination schedule up to 12 months of age, Rondonópolis, Mato Grosso.

Objective:To analyze factors associated with the incomplete timely vaccination schedule up to 12 months of age, in children born in 2015, in the municipality of Rondonópolis, Mato Grosso.Methods:Population survey, August/2017 to February/2018, which used the method proposed by the World Health Organization to collect information about routine vaccination. For analysis of the associated factors, the recommendations of the National Immunization Program of the Ministry of Health were considered. Univariate analysis was performed, and the factors associated with p<0.20 entered in the multiple analysis, with hierarchical entry of individual variables and contextual indicator of concentration of the income extremes.Results:The incomplete timely vaccination schedule up to 12 months was 82.03% (95%CI 78.41–86.63). In the final model, the following remained independently associated: having one or more siblings at home (OR 3.18; 95%CI 1.75–5.76) and not receiving a visit from a community health worker in the last 30 days (OR 1.93; 95%CI 1.04–3.57).Conclusions:It is necessary to implement an active search for children with vaccination delay in relation to the recommended interval for each vaccine, in addition to the need to strengthen the link of the family health strategy and child caregivers.

Seroprevalence of Measles Antibodies in Healthcare Professionals in a Central Hospital in Portugal

Immunity against measles may result from previous contact with the virus or vaccination. In this study we aimed to evaluate the prevalence of immunity to measles in healthcare professionals of a central hospital. Retrospective study, with description of the results of measles-specific IgG assay in healthcare professionals, between May 2010 and March 2018. The results of 1339 healthcare professionals were analyzed. The average age was 39.3 ± 10.11 years, 71.1% female. The prevalence of positive IgG was 81.5%, higher among professionals in the age groups 40 - 49 and over 50 years (91.9% and 94.6% respectively). Healthcare professionals who presented negative or equivocal IgG were mostly under 40 years old (83.1%) (p < 0.05). The prevalence of serological immunity to measles in healthcare professionals was found to be lower than in other studies. That may be due to differences between the characteristics of the studied samples. Susceptibility to measles was higher in lower age groups. These results may reflect low vaccination coverage in this age group, an incomplete vaccination schedule, or the possibility of older healthcare professionals having the disease, which may confer an immune response with higher IgG levels. Knowing the prevalence of susceptibility to measles in healthcare professionals enabled the establishment of prevention strategies for outbreaks that may occur. Vaccination remains the best preventative measure, but a third dose of vaccine may be considered in certain epidemiological contexts, particularly in the youngest exposed healthcare professionals.

Vaccine uptake and associated factors in an irregular urban settlement in northeastern Brazil: a cross-sectional study

BackgroundGlobally, childhood immunization saves the lives of 2–3 million children annually by protecting them against vaccine-preventable diseases. In 2017, 116.2 million children were vaccinated worldwide according to the World Health Organization. Nevertheless, figures suggest that 19.5 million children around the world fail to receive the benefits of complete immunization.MethodsThis cross-sectional study analyzed vaccine uptake and the factors associated with incomplete vaccination schedule in children of up to 36 months of age assisted by the family health strategy in an irregular settlement located in a state capital city in northeastern Brazil. This study was nested within a larger study entitled “Health, nutrition and healthcare services in an urban slum population in Recife, Pernambuco”, conducted in 2015. A census included 309 children, with vaccination data obtained, exclusively, from their vaccination cards records. An ad hoc database was constructed with variables of interest. Absolute and relative values were calculated for the socioeconomic, demographic, obstetric and biological data. To identify possible factors associated with incomplete vaccination schedule, crude and multivariable Poisson regression analyses were performed, and conducted in accordance with the forward selection method with robust variance and the adjusted prevalence ratio was calculated with the 95% CI. Variables with p-values < 0.20 in the unadjusted stage were included in the multivariable analysis. The statistical significance of each variable was evaluated using the Wald test, with p-values < 0.05.ResultsJust half of the children (52,1%) was classified as complete vaccination schedule. In the final model, the factors associated with incomplete vaccination schedule were age 12–36 months and the mother who did not complete high school.ConclusionThe percentage of vaccine uptake found was far below the recommendation of the National Childhood Immunization Schedule and was associated with child’s age and mother’s education level. Based on these findings, the family healthcare teams may elaborate vaccination strategies aimed at reaching the coverage rates established by the national immunization program. Optimizing coverage will ultimately prevent the resurgence, at epidemic level, of infectious diseases that are already under control in this country.

Relationship between vaccination and nutritional status in children: Analysis of recent Demographic and Health Surveys

Background: A body of evidence suggests that vaccines support the development of the immune system and also improve overall health. Objective: To study the effect of the complete basic vaccination schedule (Bacille Calmette-Guerin, i.e., BCG; measles; polio 3; and Diphtheria, Tetanus toxoids, and Pertussis, i.e., DTP3) on nutritional status of children under 2 years of age. Methods: Recent DHS data from 16 countries conducted after 2013 were used. After a bivariate descriptive analysis, a logistic regression analysis was conducted to predict the likelihood of underweight, stunting, and wasting by immunization status. A combined odds ratio was computed and adjusted for background variables. Results: A significantly higher prevalence of underweight was found among children with incomplete vaccination schedules in seven countries. Similarly, wasting and stunting were frequently observed in under-vaccinated children in four countries. Moreover, logistic regression adjusted for background variables revealed a relation between incomplete vaccination and underweight in Angola, Chad, and Guatemala (95% CI lower bound > 1). Combining data of all countries, underweight (adjusted Odds Ratio, aOR 1.21, 95% CI 1.11‒1.31), wasting (aOR 1.18, 95% CI 1.05‒1.33), and stunting (aOR 1.07, 95% CI 1.00‒1.14) were associated with poor vaccination status. The overall effect was consistent with both sexes except the results for wasting for females and stunting for males, though insignificant. Contribution: To our knowledge, this is the first paper assessing the relation between vaccination and nutritional status at a multi-country level with a huge dataset. Our analysis suggests a poor nutritional status in children with an incomplete vaccination schedule.

Children with type 1 Diabetes Mellitus: access to special immunobiological and child care.

Identifying the use of child care situations, the vaccination situation and the reasons for non-vaccination, and characterizing whether mothers/guardians demonstrate notions about the right to special vaccines for children with type 1 Diabetes Mellitus. A descriptive, cross-sectional study with analysis of quantitative data based on interviews with mothers/guardians, particularly regarding access to childcare and vaccination against influenza and pneumococcal 23-valent (PPSV). 47 mothers/guardians participated in the study. The participants reported using more specialized services to follow child health, and only a few used the child care of the basic health care regularly. There were incomplete vaccination schedules, delayed annual follow-ups, missing vaccination cards at the consultations, misinformation about the special character of the vaccination, as well as emphasis on the need of presenting a specific form to obtain the vaccination, resulting in discontinuation of health actions and missed opportunities for vaccination. Fragilities in child care and immunization actions require an increase of primary health care and of the care network, based on knowledge and the right to health in order to expand the evidence-based practice, access and comprehensiveness.

Pertussis characterization in the central-west region of São Paulo state, Brazil

Pertussis is a highly contagious respiratory disease caused by Bordetella pertussis. This study aimed at characterizing the B. pertussis laboratory positivity and the isolated strains in municipalities of the Central-West Region of São Paulo State, Brazil from 2010 to 2014. A total of 597 nasopharyngeal swabs samples were collected from suspected patients and contacts, and analyzed by in vitro culture and Real-Time PCR (qPCR). Culture-positive B. pertussis strains were characterized by serotyping and pulsed-field gel electrophoresis. Considering culture and/ or qPCR, the positivity rate was of 19.6%. Out of 117 samples with B. pertussis, 23 were detected by both methods, 89 by qPCR only and five by culture only. Strains presenting FIM3 (40%), FIM2,3 (32%) and FIM2 (28%) serotypes were found. Five pulsotypes were detected by PFGE, 48% of which identified as BP.Xba.0039, being the predominant type in this study. Among the positive strains, 50% were isolated from &lt; 2 months old-children and 17% were isolated from three to six months old patients. Non-vaccinated children or with incomplete vaccination schedule were at the major risk of complications and death, highlighting the importance of a continuous monitoring of this infection for the future control strategies.

Seroprevalence of mumps in an epidemic period in Medellín, Colombia

ObjectiveWe related seroprevalence and outbreaks data in order to identify factors that could explain the occurrence of outbreaks despite high vaccination coverage in Medellín Colombia. MethodsSamples from a population seroprevalence data obtained in 2009 in a random survey were analyzed. IgG levels were determined for mumps using 2 commercial tests of 2119 individuals aged 6–64 years. A comparative analysis was undertaken using age–specific mumps seroprevalence data and information of 98 epidemiological investigations of mumps outbreaks reported in 2009. ResultsOverall, seroprevalence was 91.6% (95% CI=89.3–93.5%). The age-specific seronegativity was 20.3% and 20.6% in age groups 11–15 years and 16–20 years respectively. Individuals aged 6–20 years were the most affected during outbreaks. In individuals born in 2003, a year after the change in the booster schedule from 10 to 5 years, the proportion of unvaccinated individuals (14%) and those who received only one dose of MMR (45%) increased substantially. On average, 23.5 days elapsed between the onset of symptoms in secondary cases and the outbreak investigation. ConclusionPotential contributing factors for the occurrence of outbreaks of mumps were the relatively high prevalence of seronegativity among individuals aged 11–20 years, delays in investigation and control of outbreaks, and incomplete vaccination schedules.

Understanding the main barriers to immunization in Colombia to better tailor communication strategies.

BackgroundThe Expanded Program on Immunization (EPI) in Colombia has made great advances since its inception in 1979; however, by 2010 vaccination coverage rates had been declining. In 2010, the EPI commissioned a nationwide study on practices on immunization, attitudes and knowledge, perceived service quality, and barriers to childhood immunization in order to tailor EPI communication strategies.MethodsColombia’s 32 geographical departments were divided into 10 regions. Interviewers from an independent polling company administered a survey to 4802 parents and guardians of children aged <5 years in these regions. To better assess barriers to vaccination, the study was designed to have 70% of participants who had children with incomplete vaccination schedules. Explanatory factorial, principal component, and cluster analyses were performed to place participants into a group (segment) representing the primary category of reasons respondents offered for not vaccinating their children. Types of barriers were then compared to other variables, such as service quality, communication preferences, and parental attitudes on vaccination.ResultsAlthough all respondents indicated that vaccines have health benefits, and 4738 (98.7%) possessed vaccination cards for their children, attitudes and knowledge were not always favorable to immunization. Six groups of immunization barriers were identified: 1) factors related to caregivers (24.4%), 2) vaccinators (19.7%), 3) health centers (18.0%), 4) the health system (13.4%), 5) concerns about adverse events (13.1%), and 6) cultural and religious beliefs (11.4%); groups 1, 5 and 6 together represented almost half (48.9%) of users, indicating problems related to the demand for vaccines as the primary barriers to immunization. Differences in demographics, communication preferences, and reported service quality were found among participants in the six groups and among participants in the 10 regions. Additionally, differences between how participants reported receiving information on vaccination and how they believed such information should be communicated were observed.ConclusionsBetter understanding immunization barriers and the users of the EPI can help tailor communication strategies to increase demand for immunization services. Results of the study have been used by Colombia’s EPI to inform the design of new communication strategies.