Routine Vaccination Coverage - Worldwide, 2022.

In 2020, the World Health Assembly endorsed the Immunization Agenda 2030 (IA2030), the 2021-2030 global strategy that envisions a world where everyone, everywhere, at every age, fully benefits from vaccines. This report reviews trends in World Health Organization and UNICEF immunization coverage estimates at global, regional, and national levels through 2022 and documents progress toward improving coverage with respect to the IA2030 strategy, which aims to reduce the number of children who have not received the first dose of a diphtheria-tetanus-pertussis-containing vaccine (DTPcv1) worldwide by 50% and to increase coverage with 3 diphtheria-tetanus-pertussis-containing vaccine doses (DTPcv3) to 90%. Worldwide, coverage ≥1 dose of DTPcv1 increased from 86% in 2021 to 89% in 2022 but remained below the 90% coverage achieved in 2019. Estimated DTPcv3 coverage increased from 81% in 2021 to 84% in 2022 but also remained below the 2019 coverage of 86%. Worldwide in 2022, 14.3 million children were not vaccinated with DTPcv1, a 21% decrease from 18.1 million in 2021, but an 11% increase from 12.9 million in 2019. Most children (84%) who did not receive DTPcv1 in 2022 lived in low- and lower-middle-income countries. COVID-19 pandemic-associated immunization recovery occurred in 2022 at the global level, but progress was unevenly distributed, especially among low-income countries. Urgent action is needed to provide incompletely vaccinated children with catch-up vaccinations that were missed during the pandemic, restore national vaccination coverage to prepandemic levels, strengthen immunization programs to build resiliency to withstand future unforeseen public health events, and further improve coverage to protect children from vaccine-preventable diseases.

Estimating global and regional disruptions to routine childhood vaccine coverage during the COVID-19 pandemic in 2020: a modelling study.

BACKGROUND: The COVID-19 pandemic and efforts to reduce SARS-CoV-2 transmission substantially affected health services worldwide. To better understand the impact of the pandemic on childhood routine immunisation, we estimated disruptions in vaccine coverage associated with the pandemic in 2020, globally and by Global Burden of Disease (GBD) super-region. METHODS: For this analysis we used a two-step hierarchical random spline modelling approach to estimate global and regional disruptions to routine immunisation using administrative data and reports from electronic immunisation systems, with mobility data as a model input. Paired with estimates of vaccine coverage expected in the absence of COVID-19, which were derived from vaccine coverage models from GBD 2020, Release 1 (GBD 2020 R1), we estimated the number of children who missed routinely delivered doses of the third-dose diphtheria-tetanus-pertussis (DTP3) vaccine and first-dose measles-containing vaccine (MCV1) in 2020. FINDINGS: Globally, in 2020, estimated vaccine coverage was 76·7% (95% uncertainty interval 74·3-78·6) for DTP3 and 78·9% (74·8-81·9) for MCV1, representing relative reductions of 7·7% (6·0-10·1) for DTP3 and 7·9% (5·2-11·7) for MCV1, compared to expected doses delivered in the absence of the COVID-19 pandemic. From January to December, 2020, we estimated that 30·0 million (27·6-33·1) children missed doses of DTP3 and 27·2 million (23·4-32·5) children missed MCV1 doses. Compared to expected gaps in coverage for eligible children in 2020, these estimates represented an additional 8·5 million (6·5-11·6) children not routinely vaccinated with DTP3 and an additional 8·9 million (5·7-13·7) children not routinely vaccinated with MCV1 attributable to the COVID-19 pandemic. Globally, monthly disruptions were highest in April, 2020, across all GBD super-regions, with 4·6 million (4·0-5·4) children missing doses of DTP3 and 4·4 million (3·7-5·2) children missing doses of MCV1. Every GBD super-region saw reductions in vaccine coverage in March and April, with the most severe annual impacts in north Africa and the Middle East, south Asia, and Latin America and the Caribbean. We estimated the lowest annual reductions in vaccine delivery in sub-Saharan Africa, where disruptions remained minimal throughout the year. For some super-regions, including southeast Asia, east Asia, and Oceania for both DTP3 and MCV1, the high-income super-region for DTP3, and south Asia for MCV1, estimates suggest that monthly doses were delivered at or above expected levels during the second half of 2020. INTERPRETATION: Routine immunisation services faced stark challenges in 2020, with the COVID-19 pandemic causing the most widespread and largest global disruption in recent history. Although the latest coverage trajectories point towards recovery in some regions, a combination of lagging catch-up immunisation services, continued SARS-CoV-2 transmission, and persistent gaps in vaccine coverage before the pandemic still left millions of children under-vaccinated or unvaccinated against preventable diseases at the end of 2020, and these gaps are likely to extend throughout 2021. Strengthening routine immunisation data systems and efforts to target resources and outreach will be essential to minimise the risk of vaccine-preventable disease outbreaks, reach children who missed routine vaccine doses during the pandemic, and accelerate progress towards higher and more equitable vaccination coverage over the next decade. FUNDING: Bill & Melinda Gates Foundation.

Routine Vaccination Coverage - Worldwide, 2021.

In 2020, the World Health Assembly endorsed the Immunization Agenda 2030, an ambitious global immunization strategy to reduce morbidity and mortality from vaccine-preventable diseases (1). This report updates a 2020 report (2) with global, regional,* and national vaccination coverage estimates and trends through 2021. Global estimates of coverage with 3 doses of diphtheria-tetanus-pertussis-containing vaccine (DTPcv3) decreased from an average of 86% during 2015-2019 to 83% in 2020 and 81% in 2021. Worldwide in 2021, 25.0 million infants (19% of the target population) were not vaccinated with DTPcv3, 2.1 million more than in 2020 and 5.9 million more than in 2019. In 2021, the number of infants who did not receive any DTPcv dose by age 12 months (18.2 million) was 37% higher than in 2019 (13.3 million). Coverage with the first dose of measles-containing vaccine (MCV1) decreased from an average of 85% during 2015-2019 to 84% in 2020 and 81% in 2021. These are the lowest coverage levels for DTPcv3 and MCV1 since 2008. ​Global coverage estimates were also lower in 2021 than in 2020 and 2019 for bacillus Calmette-Guérin vaccine (BCG) as well as for the completed series of Haemophilus influenzae type b vaccine (Hib), hepatitis B vaccine (HepB), polio vaccine (Pol), and rubella-containing vaccine (RCV). The COVID-19 pandemic has resulted in disruptions to routine immunization services worldwide. Full recovery to immunization programs will require context-specific strategies to address immunization gaps by catching up missed children, prioritizing essential health services, and strengthening immunization programs to prevent outbreaks (3).

Who gets vaccinated in a measles-rubella campaign in Nepal?: results from a post-campaign coverage survey.

BACKGROUND: Following the 2015 earthquake, a measles-rubella (MR) supplementary immunization activity (SIA), in four phases, was implemented in Nepal in 2015-2016. A post-campaign coverage survey (PCCS) was then conducted in 2017 to assess SIA performance and explore factors that were associated with vaccine uptake. METHODS: A household survey using stratified multi-stage probability sampling was conducted to assess coverage for a MR dose in the 2015-2016 SIA in Nepal. Logistic regression was then used to identify factors related to vaccine uptake. RESULTS: Eleven thousand two hundred fifty-three households, with 4870 eligible children provided information on vaccination during the 2015-2016 MR SIA. Overall coverage of measles-rubella vaccine was 84.7% (95% CI: 82.0-87.0), but varied between 77.5% (95% CI: 72.0, 82.2) in phase-3, of 21 districts vaccinated in Feb-Mar 2016, to 97.7% (CI: 95.4, 98.9) in phase-4, of the last seven mountainous districts vaccinated in Mar-Apr 2016. Coverage in rural areas was higher at 85.6% (CI: 81.9, 88.8) than in urban areas at 79.0% (CI: 75.5, 82.1). Of the 4223 children whose caregivers knew about the SIA, 96.5% received the MR dose and of the 647 children whose caregivers had not heard about the campaign, only 1.8% received the MR dose. CONCLUSIONS: The coverage in the 2015-2016 MR SIA in Nepal varied by geographical region with rural areas achieving higher coverage than urban areas. The single most important predictor of vaccination was the caregiver being informed in advance about the vaccination campaign. Enhanced efforts on social mobilization for vaccination have been used in Nepal since this survey, notably for the most recent 2020 MR campaign.

Subnational inequalities in diphtheria-tetanus-pertussis immunization in 24 countries in the African Region.

OBJECTIVE: To analyse subnational inequality in diphtheria-tetanus-pertussis (DTP) immunization dropout in 24 African countries using administrative data on receipt of the first and third vaccine doses (DTP1 and DTP3, respectively) collected by the Joint Reporting Process of the World Health Organization and the United Nations Children's Fund. METHODS: Districts in each country were grouped into quintiles according to the proportion of children who dropped out between DTP1 and DTP3 (i.e. the dropout rate). We used six summary measures to quantify inequalities in dropout rates between districts and compared rates with national dropout rates and DTP1 and DTP3 immunization coverage. FINDINGS: The median dropout rate across countries was 2.4% in quintiles with the lowest rate and 14.6% in quintiles with the highest rate. In eight countries, the difference between the highest and lowest quintiles was 14.9 percentage points or more. In most countries, underperforming districts in the quintile with the highest rate tended to lag disproportionately behind the others. This divergence was not evident from looking only at national dropout rates. Countries with the largest inequalities in absolute subnational dropout rate tended to have lower estimated national DTP1 and DTP3 immunization coverage. CONCLUSION: There were marked inequalities in DTP immunization dropout rates between districts in most countries studied. Monitoring dropout at the subnational level could help guide immunization interventions that address inequalities in underserved areas, thereby improving overall DTP3 coverage. The quality of administrative data should be improved to ensure accurate and timely assessment of geographical inequalities in immunization.

Routine Vaccination Coverage - Worldwide, 2020.

Endorsed by the World Health Assembly in 2020, the Immunization Agenda 2030 (IA2030) strives to reduce morbidity and mortality from vaccine-preventable diseases across the life course (1). This report, which updates a previous report (2), presents global, regional,* and national vaccination coverage estimates and trends as of 2020. Changes are described in vaccination coverage and the numbers of unvaccinated and undervaccinated children as measured by receipt of the first and third doses of diphtheria, tetanus, and pertussis-containing vaccine (DTP) in 2020, when the COVID-19 pandemic began, compared with 2019. Global estimates of coverage with the third dose of DTP (DTP3) and a polio vaccine (Pol3) decreased from 86% in 2019 to 83% in 2020. Similarly, coverage with the first dose of measles-containing vaccine (MCV1) dropped from 86% in 2019 to 84% in 2020. The last year that coverage estimates were at 2020 levels was 2009 for DTP3 and 2014 for both MCV1 and Pol3. Worldwide, 22.7 million children (17% of the target population) were not vaccinated with DTP3 in 2020 compared with 19.0 million (14%) in 2019. Children who did not receive the first DTP dose (DTP1) by age 12 months (zero-dose children) accounted for 95% of the increased number. Among those who did not receive DTP3 in 2020, approximately 17.1 million (75%) were zero-dose children. Global coverage decreased in 2020 compared with 2019 estimates for the completed series of Haemophilus influenzae type b (Hib), hepatitis B vaccine (HepB), human papillomavirus vaccine (HPV), and rubella-containing vaccine (RCV). Full recovery from COVID-19-associated disruptions will require targeted, context-specific strategies to identify and catch up zero-dose and undervaccinated children, introduce interventions to minimize missed vaccinations, monitor coverage, and respond to program setbacks (3).

Characterization of immunization secondary analyses using demographic and health surveys (DHS) and multiple indicator cluster surveys (MICS), 2006-2018.

BACKGROUND: Infant immunization coverage worldwide has plateaued at about 85%. Using existing survey data to conduct analyses beyond estimating coverage may help immunization programmes better tailor strategies to reach un- and under-immunized children. The Demographic and Health Survey (DHS) and the Multiple Indicators Cluster Survey (MICS), routinely conducted in low and middle-income countries (LMICs), collect immunization data, yet vaccination coverage is often the only indicator reported and used. We conducted a review of published immunization-related analyses to characterize and quantify immunization secondary analyses done using DHS and MICS databases. METHODS: We conducted a systematic search of the literature, of immunization-related secondary analyses from DHS or MICS published between 2006 and August 2018. We searched 15 electronic databases without language restrictions. For the articles included, relevant information was extracted and analyzed to summarize the characteristics of immunization-related secondary analyses. Results are presented following the PRISMA guidelines. RESULTS: Among 1411 papers identified, 115 met our eligibility criteria; additionally, one article was supplemented by the Pan American Health Organization. The majority were published since 2012 (77.6%), and most (68.9%) had a first or corresponding author affiliated with institutions in high-income countries (as opposed to LMICs where these surveys are conducted). The median delay between survey implementation and publication of the secondary analysis was 5.4 years, with papers with authors affiliated to institutions in LMIC having a longer median publication delay (p < 0.001). Over 80% of the published analyses looked at factors associated with a specific vaccine or with full immunization. Quality proxies, such as reporting percent of immunization data from cards vs recall; occurrence and handling of missing data; whether survey analyses were weighted; and listing of potential biases or limitations of the original survey or analyses, were infrequently mentioned. CONCLUSION: Our review suggests that more needs to be done to increase the increase the utilization of existing DHS and MICS datasets and improve the quality of the analyses to inform immunization programmes. This would include increasing the proportion of analyses done in LMICs, reducing the time lag between survey implementation and publication of additional analyses, and including more qualitative information about the survey in the publications to better interpret the results.

Vaccination coverage in Lebanon following the Syrian crisis: results from the district-based immunization coverage evaluation survey 2016.

BACKGROUND: Following the Syrian crisis, a substantial influx of Syrian refugees into Lebanon posed new challenges to optimal vaccination coverage for all children residing in the country. In 2016, the district-based immunization coverage evaluation survey (CES) assessed routine immunization coverage at the district level in Lebanon among children aged 12-59 months. METHODS: A cross-sectional multistage cluster survey was conducted in all of Lebanon (with the exception of the Nabatieh district) using the World Health Organization (WHO) recommended Expanded Programme on Immunization (EPI) methodology adapted to the local context. A survey questionnaire consisting of closed and open-ended questions concerning demographic information and the child's immunization status was administered to collect immunization status information. RESULTS: Among surveyed children aged 12-59 months, irrespective of nationality, vaccination coverage at the national level for any recommended last dose was below the targeted 95%. Generally, vaccination coverage levels increased with age and were higher among Lebanese than Syrian children. However, large variations were revealed when coverage rates were analyzed at the district level. Vaccination was significantly associated with nationality, age, mother's educational status and the place of vaccination. Common reasons for undervaccination included the child's illness at the time of vaccine administration, vaccination fees, lack of awareness or a doctor's advice not to vaccinate during campaigns. CONCLUSIONS: Substantial variability exists in vaccination coverage among children aged 12-59 months residing in different districts in Lebanon. Immunization coverage reached 90% or above only for the first doses of polio and pentavalent vaccines. A considerable dropout rate from the first dose of any vaccine is observed. Efforts to optimize coverage levels should include increased vaccination initiatives targeting both refugee children and children from vulnerable host communities, increased cooperation between public and private vaccine providers, improved training for vaccine providers to adhere to complete vaccine administration recommendations, and increased awareness among caregivers.

Assessing electronic immunization registries: the Pan American Health Organization experience.

OBJECTIVE: To develop a methodology to assess electronic immunization registries (EIRs) in low- and middle-income countries (LMICs) in Latin America and the Caribbean. METHODS: A team from the Immunization Unit at the Pan American Health Organization (PAHO) reviewed existing methodologies to evaluate health information systems, particularly the Performance of Routine Information System Management (PRISM) framework and methodologies used to assess information systems. In 2014, the PAHO team convened a small working group to develop an evaluation approach to be added to the existing World Health Organization immunization data quality self-assessment (DQS) tool. The resulting DQS with an added EIR component was named "DQS Plus." The DQS Plus methodology was used in Panama in May 2014 and in Honduras in November 2015. RESULTS: The DQS Plus tool proved feasible and easy to implement in Panama and Honduras, including by not adding much time or resources to those needed for a usual DQS. The information obtained from the DQS Plus assessment was practical and helped provide health authorities with recommendations to update and improve their EIR, strengthen the use of the registry, and enhance the data the assessment produced, at all levels of the health system. These recommendations are currently being implemented in the two countries. CONCLUSIONS: The DQS Plus proved to be a practical and useful approach for assessing an EIR in an LMIC and generating actionable recommendations. Further work on defining operational and related EIR functional standards in LMICs will help develop an improved EIR assessment tool for Latin America and the Caribbean, and potentially elsewhere.

MMR2 vaccination coverage and timeliness among children born in 2004 - 2009: a national survey in Saint Lucia, 2015.

OBJECTIVES: To more accurately determine coverage and timeliness of the second dose of measles-mumps-rubella vaccine (MMR2), while identifying factors associated with low MMR2 vaccination uptake among children in Saint Lucia. METHODS: A survey was conducted in October - November 2015 targeting children born in 2004 - 2009. At 86 preschools and primary schools, two children from each grade were randomly selected, yielding an effective sample of 836 children. Health records were reviewed to assess vaccination coverage and timeliness. Parents and/or guardians and principals of all 86 schools were interviewed regarding knowledge, attitudes, and practices related to vaccination. RESULTS: Of 767 children included, 75% were vaccinated with MMR2 (n = 572); 46.7% were vaccinated in a timely manner, i.e., by 5 years of age. Cohorts born in 2004, 2005, and 2008 reported the lowest proportion. 'Mothers as caregivers' was positively associated with timely MMR2 vaccination. Although 97% of principals surveyed considered vaccination important, 48.8% were not aware of national legislation requiring complete vaccination prior to school entry. Survey results concurred with the low MMR2 administrative coverage rates reported by Saint Lucia, much lower than the recommended 95%. CONCLUSIONS: Based on the results of this survey, Saint Lucia's national immunization program has lowered the age of MMR2 to 18 months in 2016, increased advocacy with schools to enforce the school-entry law, and is working to vaccinate the cohorts of children who have not received timely MMR2.

[Experience with development of tools to monitor vaccination coverage and preventive chemotherapy coverageExperiência do desenvolvimento de ferramentas para o monitoramento da cobertura vacinal e quimioprofilaxia]. / Experiencia del desarrollo de herramientas para el monitoreo de coberturas de vacunación y quimioterapia preventiva.

OBJETIVO: Describir la experiencia y las lecciones aprendidas en el desarrollo de herramientas para el monitoreo de las coberturas de vacunación y de quimioterapia preventiva en las Américas. MÉTODOS: Se compiló y revisó la documentación disponible en los programas regionales de inmunización integral de la familia y de las enfermedades infecciosas desatendidas de la Organización Panamericana de la Salud/Organización Mundial de la Salud producida durante el proceso de desarrollo de las herramientas entre 2012 y 2017 incluidos: búsqueda sistemática de literatura, reportes técnicos, informes de reuniones internas, reporte de la prueba piloto e informes y resultados de las evaluaciones de los talleres de entrenamiento en doce países de las Américas. La documentación se organizó, se extrajo la información más relevante sobre el desarrollo de las herramientas y se consensuaron las principales lecciones aprendidas en el proceso. RESULTADOS: El proceso facilitó la organización y sistematización de las herramientas aplicadas durante las últimas dos décadas en los programas de vacunación en las Américas para el análisis y monitoreo de las coberturas y su rápida adaptación para el monitoreo de las coberturas de la quimioterapia preventiva. Se integró un conjunto de herramientas cuya aplicación se define con un algoritmo de decisiones y pueden ser utilizadas por los países. CONCLUSIONES: Las lecciones aprendidas pueden aplicarse para desarrollos similares y para promover el trabajo interprogramático en salud pública. El trabajo integrado aceleró el desarrollo de herramientas útiles para los países.

OBJETIVO: Descrever a experiência e as lições aprendidas no desenvolvimento de ferramentas para o monitoramento da cobertura vacinal e quimioprofilaxia nas Américas. MÉTODOS: Foi coletada e revisada a documentação disponível nos programas regionais de imunização integral da família e doenças infecciosas negligenciadas da Organização Pan-Americana da Saúde/Organização Mundial da Saúde, produzida no processo de desenvolvimento de ferramentas entre 2012 e 2017. Os arquivos englobavam resultados de busca sistemática da literatura, relatórios técnicos, atas de reuniões internas, informe de teste-piloto e relatórios e resultados das avaliações dos seminários de capacitação em 12 países das Américas. A documentação foi organizada e foram extraídos os dados mais relevantes sobre o desenvolvimento das ferramentas. As principais lições aprendidas no processo foram decididas por consenso. RESULTADOS: O processo facilitou a organização e a sistematização das ferramentas empregadas nas últimas duas décadas nos programas de vacinação nas Américas para avaliação e monitoramento da cobertura vacinal e sua rápida adaptação para o monitoramento da cobertura da quimioprofilaxia. Foi integrado um conjunto de ferramentas cuja aplicação é definida com um algoritmo de decisões e que pode ser utilizado pelos países. CONCLUSÕES: As lições aprendidas podem ser aplicadas em processos semelhantes de desenvolvimento e para promover o trabalho interprogramático em saúde pública. O trabalho integrado acelerou o desenvolvimento de ferramentas úteis para os países.

Global Routine Vaccination Coverage, 2015.

In 1974, the World Health Organization (WHO) established the Expanded Program on Immunization* to provide protection against six vaccine-preventable diseases through routine infant immunization (1). Based on 2015 WHO and United Nations Children's Fund (UNICEF) estimates, global coverage with the third dose of diphtheria-tetanus-pertussis vaccine (DTP3), the first dose of measles-containing vaccine (MCV1) and the third dose of polio vaccine (Pol3) has remained stable (84%-86%) since 2010. From 2014 to 2015, estimated global coverage with the second MCV dose (MCV2) increased from 39% to 43% by the end of the second year of life and from 58% to 61% when older age groups were included. Global coverage was higher in 2015 than 2010 for newer or underused vaccines, including rotavirus vaccine, pneumococcal conjugate vaccine (PCV), rubella vaccine, Haemophilus influenzae type b (Hib) vaccine, and 3 doses of hepatitis B (HepB3) vaccine. Coverage estimates varied widely by WHO Region, country, and district; in addition, for the vaccines evaluated (MCV, DTP3, Pol3, HepB3, Hib3), wide disparities were found in coverage by country income classification. Improvements in equity of access are necessary to reach and sustain higher coverage and increase protection from vaccine-preventable diseases for all persons.

Vaccination Week in the Americas, 2011: an opportunity to assess the routine vaccination program in the Bolivarian Republic of Venezuela.

BACKGROUND: Vaccination Week in the Americas (VWA) is an annual initiative in countries and territories of the Americas every April to highlight the work of national expanded programs on immunization (EPI) and increase access to vaccination services for high-risk population groups. In 2011, as part of VWA, Venezuela targeted children aged less than 6 years in 25 priority border municipalities using social mobilization to increase institution-based vaccination. Implementation of social communication activities was decentralized to the local level. We conducted a survey in one border municipality of Venezuela to evaluate the outcome of VWA 2011 and provide a snapshot of the overall performance of the routine EPI at that level. METHODS: We conducted a coverage survey, using stratified cluster sampling, in the Venezuelan municipality of Bolivar (bordering Colombia) in August 2011. We collected information for children aged <6 years through caregiver interviews and transcription of vaccination card data. We estimated each child's eligibility to receive a specific vaccine dose during VWA 2011 and whether or not they were actually vaccinated during VWA activities. We also estimated baseline vaccination coverage, timeliness and 95% confidence intervals (CI), and used chi-square tests to compare coverage across age cohorts, taking into account the sampling design. RESULTS: We surveyed 839 children from 698 households; 93% of children had a vaccination card. Among households surveyed, 216 (31%) caregivers reported having heard about a vaccination activity during April or May 2011. Of the 528 children eligible to receive a vaccine during VWA, 24% received at least one dose, while 13% received all doses due. Overall, baseline coverage with routine vaccines, as measured by the survey, was >85%, with a few exceptions. CONCLUSION: Low levels of VWA awareness among caregivers probably contributed to the limited vaccination of eligible children during the VWA activities in Bolivar in 2011. However, vaccine coverage for most EPI vaccines was high. Additionally, high vaccination card availability and high participation in VWA among those caregivers aware of it in 2011 suggest public trust in the EPI program in the municipality. Health authorities have used survey findings to inform changes to the routine EPI and better VWA implementation in subsequent years.

Lessons learned from the development of a new methodology to assess missed opportunities for vaccination in Latin America and the Caribbean.

The Pan American Health Organization recently developed a practical guide for evaluating missed opportunities for vaccination among children aged <5 years. A missed opportunity occurs when an individual eligible for vaccination has contact with a health facility and does not receive a needed vaccine, despite having no contraindications. In this article, we discuss the strengths and limitations of this new methodology and present lessons learned from recent studies on undervaccination in Latin America. Our findings should be useful to countries embarking on assessing the magnitude and the causes of missed opportunities for vaccination children experience at health facilities.

Diphtheria in the Dominican Republic: reduction of cases following a large outbreak.

OBJECTIVE: To describe the most recent outbreak of diphtheria in the Dominican Republic and the disease's occurrence and vaccination coverage in 2004-2013. METHODS: Clinical data of diphtheria cases that occurred in 2004 and that met the study's case definition were reviewed along with socioeconomic and epidemiological information from the cases' families. Univariate and multivariate analyses were performed to assess risk factors for fatal diphtheria. Routine surveillance and vaccination coverage data are presented. RESULTS: From January 2004-April 2005, a total of 145 diphtheria cases were reported; 80 (66%) of the 122 cases reported in 2004 met the case definition; 26 were fatal (case-fatality rate: 32.5%). Incidence was highest in the group 1-4 years of age at 5.3 per 100 000; 62.5% were male. Of the 80 cases, 61 (76%) where hospitalized in Hospital A, 17 in Hospital B, and 2 in two other hospitals. Earlier onset (first half of 2004), birth order, and tracheotomy were associated with fatal diphtheria (P < 0.05); cases in Hospital A were also more likely to be fatal (P = 0.066). The average annual diphtheria incidence was 4.91 cases/1 million people in 2000-2003, climbed to 8.8 cases per million in 2004-2005, and dropped to 0.38 in 2006-2014; no diphtheria cases have been reported since 2011. DTP3 vaccination coverage ranged from 72%-81% in 2000-2004 and from 81%-89% in 2005-2013. CONCLUSIONS: The 2004-2005 diphtheria outbreak in the Dominican Republic resulted in important and avoidable morbidity and mortality. Annual cases declined and no cases have been reported in recent years. Maintaining high vaccination coverage and diligent surveillance are crucial to preventing diphtheria outbreaks and controlling the disease.

Vaccine-associated paralytic poliomyelitis in the postelimination era in Latin America and the Caribbean, 1992-2011.

The Americas interrupted the transmission of poliovirus in 1991; most Latin American and Caribbean (LAC) countries rely on the oral polio vaccine (OPV) to maintain elimination. We estimated the risk of vaccine-associated paralytic polio (VAPP) in LAC for 1992-2011. VAPP cases were identified using LAC's acute flaccid paralysis (AFP) surveillance system. VAPP was defined as any AFP case with residual paralysis 60 days following onset that did not have a clear alternative etiology and with isolation of vaccine-strain poliovirus. Recipient VAPP cases were defined as those with paralysis onset 4-40 days following OPV; cases meeting these criteria but with unknown residual paralysis were added. Nonrecipient VAPP cases were defined as those in individuals with an unknown vaccination status, those in individuals who received 0 doses, or those with paralysis onset outside the 4-40-day interval. Of 40 926 AFP cases reported in LAC from 1992-2011, we identified 72 recipient and 119 nonrecipient VAPP cases. The estimated risk of recipient VAPP was 1 case per 3.15 million newborns (95% confidence interval [CI], 1 case per 2.56-4.10 million newborns), and the estimated overall risk was 1 case per 1.19 million newborns (95% CI, 1 case per 1.04-1.39 million newborns). In this multicountry VAPP analysis in a postelimination period, we found that the risk of VAPP in LAC was lower than previously estimated.

Measles and rubella vaccination coverage in Haiti, 2012: progress towards verifying and challenges to maintaining measles and rubella elimination.

OBJECTIVES: We conducted a nationwide survey to assess measles containing vaccine (MCV) coverage among children aged 1-9 years in Haiti and identify factors associated with vaccination before and during the 2012 nationwide supplementary immunisation activities (SIA). METHODS: Haiti was stratified into five geographic regions (Metropolitan Port-au-Prince, North, Centre, South and West), 40 clusters were randomly selected in each region, and 35 households were selected per cluster. RESULTS: Among the 7000 visited households, 75.8% had at least one child aged 1-9 years; of these, 5279 (99.5%) households consented to participate in the survey. Of 9883 children enrolled, 91% received MCV before and/or during the SIA; 31% received MR for the first time during the SIA, and 50.7% received two doses of MCV (one before and one during the 2012 SIA). Among the 1685 unvaccinated children during the SIA, the primary reason of non-vaccination was caregivers not being aware of the SIA (31.0%). Children aged 1-4 years had significantly lower MR SIA coverage than those aged 5-9 years (79.5% vs. 84.8%) (P < 0.0001). A higher proportion of children living in the West (12.3%) and Centre (11.2%) regions had never been vaccinated than in other regions (4.8-9.1%). Awareness, educational level of the mother and region were significantly associated with MR vaccination during and before the SIA (P < 0.001). CONCLUSIONS: The 2012 SIA successfully increased MR coverage; however, to maintain measles and rubella elimination, coverage needs to be further increased among children aged 1-4 years and in regions with lower coverage.

From the parents' perspective: a user-satisfaction survey of immunization services in Guatemala.

BACKGROUND: Immunization coverage levels in Guatemala have increased over the last two decades, but national targets of ≥95% have yet to be reached. To determine factors related to undervaccination, Guatemala's National Immunization Program conducted a user-satisfaction survey of parents and guardians of children aged 0-5 years. Variables evaluated included parental immunization attitudes, preferences, and practices; the impact of immunization campaigns and marketing strategies; and factors inhibiting immunization. METHODS: Based on administrative coverage levels and socio-demographic indicators in Guatemala's 22 geographical departments, five were designated as low-coverage and five as high-coverage areas. Overall, 1194 parents and guardians of children aged 0-5 years were interviewed in these 10 departments. We compared indicators between low- and high-coverage areas and identified risk factors associated with undervaccination. RESULTS: Of the 1593 children studied, 29 (1.8%) were determined to be unvaccinated, 458 (28.8%) undervaccinated, and 1106 (69.4%) fully vaccinated. In low-coverage areas, children of less educated (no education: RR=1.49, p=0.01; primary or less: 1.39, p=0.009), older (aged>39 years: RR=1.31, p=0.05), and single (RR=1.32, p=0.03) parents were more likely to have incomplete vaccination schedules. Similarly, factors associated with undervaccination in high-coverage areas included the caregiver's lack of education (none: RR=1.72, p=0.0007; primary or less: RR=1.30, p=0.05) and single marital status (RR=1.36, p=0.03), as well as the child's birth order (second: RR=1.68, p=0.003). Although users generally approved of immunization services, problems in service quality were identified. According to participants, topics such as the risk of adverse events (47.4%) and next vaccination appointments (32.3%) were inconsistently communicated to parents. Additionally, 179 (15.0%) participants reported the inability to vaccinate their child on at least one occasion. Compared to high-coverage areas, participants in low-coverage areas reported poorer service, longer wait times, and greater distances to health centers. In high-coverage areas, participants reported less knowledge about the availability of services. CONCLUSIONS: Generally, immunization barriers in Guatemala are related to problems in accessing and attaining high-quality immunization services rather than to a population that does not adequately value vaccination. We provide recommendations to aid the country in maintaining its achievements and addressing new challenges.

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

BACKGROUND: The 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. METHODS: Colombia'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. RESULTS: Although 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. CONCLUSIONS: Better 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.