District-level estimation of vaccination coverage: Discrete vs continuous spatial models.
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ABSTRACT:
SUBMITTER: Utazi CE
PROVIDER: S-EPMC8638675 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:BackgroundDespite recent success towards controlling poliovirus transmission, Nigeria has struggled to achieve uniformly high routine vaccination coverage. A lack of reliable vaccination coverage data at the operational level makes it challenging to target program improvement. To reliably estimate vaccination coverage, we conducted district-level vaccine coverage surveys using a pre-existing infrastructure of polio technical staff in northern Nigeria.MethodsHousehold-level cluster surveys were conducted in 40 polio high risk districts of Nigeria during 2014-2015. Global positioning system technology and intensive supervision by a pool of qualified technical staff were used to ensure high survey quality. Vaccination status of children aged 12-23 months was documented based on vaccination card or caretaker's recall. District-level coverage estimates were calculated using survey methods.ResultsData from 7,815 children across 40 districts were analyzed. District-level coverage with the third dose of diphtheria-pertussis-tetanus vaccine (DPT3) ranged widely from 1-63%, with all districts having DPT3 coverage below the target of 80%. Median coverage across all districts for each of eight vaccine doses (1 Bacille Calmette-Guérin dose, 3 DPT doses, 3 oral poliovirus vaccine doses, and 1 measles vaccine dose) was <50%. DPT3 coverage by survey was substantially lower (range: 28%-139%) than the 2013 administrative coverage reported among children aged <12 months. Common reported reasons for non-vaccination included lack of knowledge about vaccines and vaccination services (50%) and factors related to access to routine immunization services (15%).ConclusionsSurvey results highlighted vaccine coverage gaps that were systematically underestimated by administrative reporting across 40 polio high risk districts in northern Nigeria. Given the limitations of administrative coverage data, our approach to conducting quality district-level coverage surveys and providing data to assess and remediate issues contributing to poor vaccination coverage could serve as an example in countries with sub-optimal vaccination coverage, similar to Nigeria.
| S-EPMC5148043 | biostudies-literature
Project description:BackgroundThe Global Vaccine Action Plan (GVAP) Monitoring and Accountability Framework includes an indicator to reach 90% national vaccination coverage and 80% vaccination coverage in every district or equivalent administrative unit with three doses of diphtheria-tetanus-pertussis containing vaccines (DTP) across all 194 country signatories to GVAP by 2020. Assessment of progress against the district indicator component requires GVAP defined "valid" coverage. GVAP defines district coverage "valid" if the WHO and UNICEF estimate of national immunization coverage for DTP3 in the most recent year is 1) ≥90%, or 2) is identical to the reported national administrative coverage for DTP3 (regardless of coverage level). We draw attention to the potential disconnect that currently exists between GVAP vaccination coverage indicators and the practical capacity to monitor progress against those indicators.MethodsWe obtained national and aggregated district coverage data for the third dose of DTP containing vaccine (DTP3) for 194 countries for 2016 from publicly available databases maintained by the World Health Organization (WHO). We reviewed district line lists of coverage data for 96 countries for which district line lists of DTP3 coverage were available and categorized the district coverage values using the same groupings used by the GVAP Monitoring Framework. In doing so, we also tracked the number of districts with reported coverage >100%.ResultsIn 2016, at least one district with DTP3 coverage value >100% was reported in the line lists of 76 of the 96 countries. Agreement in district coverage categories across each of five coverage groupings (<50%, 50-79%, 80-89%, 90-94%, ≥95%) was observed in 43 of the 96 countries. In 2016, 46 of 194 countries were classified as achieving both national DTP3 coverage ≥90% and DTP3 coverage ≥80% in every district, thereby achieving the GVAP target. Among these 46 countries, 22 countries reported district line-listing coverage data. We identified 10 of the 22 countries that reported at least one district with DTP3 coverage >100% ranging from 8% of districts in Sri Lanka to 97% of districts in Bangladesh. Seven countries reported at least 25% of the total districts had DTP3 coverage >100%.ConclusionsThe observations of disparate district coverage from a subset of countries reporting district line lists of coverage data are a concern for the current GVAP approach ascribing the achievement of "valid" district coverage data. Our review of district line lists of coverage data does not support a current GVAP assumption that the district coverage values ≥80% fall between 80% and 100% (inclusive). We hope these results spur a review of the current approach to assess the GVAP coverage target of ≥90% national DTP3 coverage and ≥80% DTP3 coverage in all districts.
| S-EPMC6030671 | biostudies-literature
Project description:We consider the analysis of longitudinal data of multiple types of events where some of the events are observed on a coarser level (e.g. grouped) at some time points during the follow-up, for example, when certain events, such as disease progression, are only observable during parts of follow-up for some subjects, causing gaps in the data, or when the time of death is observed but the cause of death is unknown. In this case, there is missing data in key characteristics of the event history such as onset, time in state, and number of events. We derive the likelihood function, score and observed information under independent and non-informative coarsening, and conduct a simulation study where we compare bias, empirical standard errors, and confidence interval coverage of estimators based on direct maximum likelihood, Monte Carlo Expectation Maximisation, ignoring the coarsening thus acting as if no event occurred, and artificial right censoring at the first time of coarsening. Longitudinal data on drug prescriptions and survival in men receiving palliative treatment for prostate cancer is used to estimate the parameters of one of the data-generating models. We demonstrate that the performance depends on several factors, including sample size and type of coarsening.
| S-EPMC10119900 | biostudies-literature
Project description:The Experience Sampling Method is a common approach in psychological research for collecting intensive longitudinal data with high ecological validity. One characteristic of ESM data is that it is often unequally spaced, because the measurement intervals within a day are deliberately varied, and measurement continues over several days. This poses a problem for discrete-time (DT) modeling approaches, which are based on the assumption that all measurements are equally spaced. Nevertheless, DT approaches such as (vector) autoregressive modeling are often used to analyze ESM data, for instance in the context of affective dynamics research. There are equivalent continuous-time (CT) models, but they are more difficult to implement. In this paper we take a pragmatic approach and evaluate the practical relevance of the violated model assumption in DT AR(1) and VAR(1) models, for the N = 1 case. We use simulated data under an ESM measurement design to investigate the bias in the parameters of interest under four different model implementations, ranging from the true CT model that accounts for all the exact measurement times, to the crudest possible DT model implementation, where even the nighttime is treated as a regular interval. An analysis of empirical affect data illustrates how the differences between DT and CT modeling can play out in practice. We find that the size and the direction of the bias in DT (V)AR models for unequally spaced ESM data depend quite strongly on the true parameter in addition to data characteristics. Our recommendation is to use CT modeling whenever possible, especially now that new software implementations have become available.
| S-EPMC5655034 | biostudies-literature
Project description:BackgroundFollowing 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.MethodsA 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.ResultsAmong 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.ConclusionsSubstantial 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.
| S-EPMC6332691 | biostudies-literature
Project description:Since Kermack and McKendrick have introduced their famous epidemiological SIR model in 1927, mathematical epidemiology has grown as an interdisciplinary research discipline including knowledge from biology, computer science, or mathematics. Due to current threatening epidemics such as COVID-19, this interest is continuously rising. As our main goal, we establish an implicit time-discrete SIR (susceptible people–infectious people–recovered people) model. For this purpose, we first introduce its continuous variant with time-varying transmission and recovery rates and, as our first contribution, discuss thoroughly its properties. With respect to these results, we develop different possible time-discrete SIR models, we derive our implicit time-discrete SIR model in contrast to many other works which mainly investigate explicit time-discrete schemes and, as our main contribution, show unique solvability and further desirable properties compared to its continuous version. We thoroughly show that many of the desired properties of the time-continuous case are still valid in the time-discrete implicit case. Especially, we prove an upper error bound for our time-discrete implicit numerical scheme. Finally, we apply our proposed time-discrete SIR model to currently available data regarding the spread of COVID-19 in Germany and Iran.
| S-EPMC7538854 | biostudies-literature
Project description:BACKGROUND:As India already missed maternal and child health related millennium development goals, the maternal and child health outcomes are a matter of concern to achieve sustainable development goals (SDGs). This study is focused to assess the gap in coverage and inequality of various reproductive, maternal, neonatal and child health (RMNCH) indicators in 640 districts of India, using data from most recent round of National Family Health Survey. METHODS:A composite index named Coverage Gap Index (CGI) was calculated, as the weighted average of eight preventive maternal and child care interventions at different administrative levels. Bivariate and spatial analysis were used to understand the geographical diversity and spatial clustering in districts of India. A socio-economic development index (SDI) was also derived and used to assess the interlinkages between CGI and development. The ratio method was used to assess the socio-economic inequality in CGI and its component at the national level. RESULTS:The average national CGI was 26.23% with the lowest in Kerala (10.48%) and highest in Nagaland (55.07%). Almost half of the Indian districts had CGI above the national average and mainly concentrated in high focus states and north-eastern part. From the geospatial analysis of CGI, 122 districts formed hotspots and 164 districts were in cold spot. The poorest households had 2.5 times higher CGI in comparison to the richest households and rural households have 1.5 times higher CGI as compared to urban households. CONCLUSION:Evidence from the study suggests that many districts in India are lagging in terms of CGI and prioritize to achieve the desired level of maternal and child health outcomes. Efforts are needed to reduce the CGI among the poorest and rural resident which may curtail the inequality.
| S-EPMC6961337 | biostudies-literature
Project description:BackgroundYoung children have a great disease burden and are particularly vulnerable to influenza. This study aimed to assess the direct effect of influenza vaccination among children and to evaluate the indirect benefit of immunizing children.MethodsThe influenza vaccination records for all children born during 2013-2019 in Minhang District and surveillance data for reported influenza cases were obtained from the Minhang CDC. 17,905 children were recorded in the vaccination system and included in this study. Descriptive epidemiology methods were used for data analysis, including an ecological approach to estimate the number of influenza cases averted by vaccination and linear regression to estimate the reduction in influenza cases in the general population per thousand additional childhood vaccination doses.ResultsDuring the study period, the annual vaccination coverage rate ranged from 10.40% in 2013-2014 to 27.62% in 2015-2016. The estimated number of influenza cases averted by vaccination ranged from a low of 0.28 (range: 0.23-0.34) during 2013-2014 (PF: 6.15%, range: 5.11-7.38%) to a high of 15.34 (range: 12.38-18.51) during 2017-2018 (PF: 16.54%, range: 13.79-19.30%). When increasing vaccination coverage rate by 10% in each town/street, a ratio of 7.27-10.69% cases could be further averted on the basis of observed cases. In four selected periods, the number of influenza cases in the general population was most significantly correlated with the cumulative childhood vaccination doses in the prior 2-5 months, and the reduction in influenza cases ranged from 0.73 to 3.18 cases per thousand additional childhood vaccination doses.ConclusionInfluenza vaccination among children is estimated to have direct effects in terms of averted cases and might provide an underlying indirect benefit to the general population. Vaccination coverage in high-coverage areas should be further expanded to avert more influenza cases.
| S-EPMC10499390 | biostudies-literature
Project description:Classical approaches to estimate vaccine efficacy are based on the assumption that a person's risk of infection does not depend on the infection status of others. This assumption is untenable for infectious disease data where such dependencies abound. We present a novel approach to estimating vaccine efficacy in a Bayesian framework using disease transmission models. The methodology is applied to outbreaks of mumps in primary schools in the Netherlands. The total study population consisted of 2,493 children in ten primary schools, of which 510 (20%) were known to have been infected, and 832 (33%) had unknown infection status. The apparent vaccination coverage ranged from 12% to 93%, and the apparent infection attack rate varied from 1% to 76%. Our analyses show that vaccination reduces the probability of infection per contact substantially but not perfectly ([Formula: see text]?=?0.933; 95CrI: 0.908-0.954). Mumps virus appears to be moderately transmissible in the school setting, with each case yielding an estimated 2.5 secondary cases in an unvaccinated population ([Formula: see text]?=?2.49; 95%CrI: 2.36-2.63), resulting in moderate estimates of the critical vaccination coverage (64.2%; 95%CrI: 61.7-66.7%). The indirect benefits of vaccination are highest in populations with vaccination coverage just below the critical vaccination coverage. In these populations, it is estimated that almost two infections can be prevented per vaccination. We discuss the implications for the optimal control of mumps in heterogeneously vaccinated populations.
| S-EPMC3642050 | biostudies-literature
Project description:There is limited understanding of why routine immunization (RI) coverage improves in some settings in Africa and not in others. Using a grounded theory approach, we conducted in-depth case studies to understand pathways to coverage improvement by comparing immunization programme experience in 12 districts in three countries (Ethiopia, Cameroon and Ghana). Drawing on positive deviance or assets model techniques we compared the experience of districts where diphtheria-tetanus-pertussis (DTP3)/pentavalent3 (Penta3) coverage improved with districts where DTP3/Penta3 coverage remained unchanged (or steady) over the same period, focusing on basic readiness to deliver immunization services and drivers of coverage improvement. The results informed a model for immunization coverage improvement that emphasizes the dynamics of immunization systems at district level. In all districts, whether improving or steady, we found that a set of basic RI system resources were in place from 2006 to 2010 and did not observe major differences in infrastructure. We found that the differences in coverage trends were due to factors other than basic RI system capacity or service readiness. We identified six common drivers of RI coverage performance improvement-four direct drivers and two enabling drivers-that were present in well-performing districts and weaker or absent in steady coverage districts, and map the pathways from driver to improved supply, demand and coverage. Findings emphasize the critical role of implementation strategies and the need for locally skilled managers that are capable of tailoring strategies to specific settings and community needs. The case studies are unique in their focus on the positive drivers of change and the identification of pathways to coverage improvement, an approach that should be considered in future studies and routine assessments of district-level immunization system performance.
| S-EPMC4353894 | biostudies-other