Investigating the contribution of geographic accessibility and vaccine delivery channels to untimely measles vaccination and zero-dose prevalence in The Gambia: implications for disease outbreaks

仅在2021年，全球就有2500万儿童没有接种第一剂白喉-破伤风-百日咳疫苗， 含疫苗（DTP 1）。其中绝大多数-生活在低收入和中等收入- 收入国家。此外，许多儿童接种了第一剂麻疹疫苗 （MCV 1）比预定时间晚得多，因此，在他们最终被感染之前， 接种疫苗，并可能有助于次优群体免疫力。在冈比亚， 麻疹，与2020年的数字相比，截至2022年年中的病例增加了6倍，尽管实现了 在过去十年中MCV 1的最低覆盖率为90%。最近的数据显示， 根据国家疫苗接种计划， Windows.此外，不合时宜的MCV 1和零剂量被认为是共存的，并聚集在某些偏远地区。 社区，并可能有助于次优的群体免疫力。主要研究者Oghenebrandi Wariri博士将使用新型 时空建模方法，以绘制麻疹疫苗接种不及时和零疫苗接种的亚群， 在精细的空间尺度上剂量，并检查与次优群体免疫力和麻疹风险的潜在联系 爆发。他还将研究地理可达性如何塑造日常生活的吸收和交付 在冈比亚接种疫苗。该项目将利用来自健康和人口统计学的纵向队列数据， 冈比亚的监测系统和冈比亚农村人口的生物库血清样本 冈比亚的Kiang West区。K43奖项有四个具体目标：1）确定 冈比亚高空间分辨率下过早MCV 1和零剂量儿童的时空模式; 2） 确定不合时宜的MCV 1和麻疹的聚集位置之间是否存在时空关系 冈比亚的人口免疫力; 3）调查地理可及性（ 家庭和疫苗接种站之间;以及固定疫苗接种站和外展疫苗接种站之间） 和延迟MCV 1; 4）模拟常规疫苗接种服务的地理可及性，以了解 目前的疫苗供应渠道，并可能确定疫苗接种诊所和接种站的最佳地点。 这个K43奖将使Wariri博士在地理空间和传染病方面拥有新的技能和能力 模特、手稿和赠款写作。瓦里里博士将与一个多学科指导委员会合作， 由国际公认的非洲、英国和美国疫苗学、人群免疫学和免疫学专家组成， 传染病建模和地理空间建模。拟议的研究与一项 结构化的指导和培训计划，包括教学课程和讲习班，旨在促进 博士- 制定独立供资的传染病和空间流行病学的长期目标 一项研究计划集中在非洲的疫苗接种，与福格蒂国际的使命一致 中心.

In 2021 alone, 25 million children globally did not receive the first dose of the diphtheria-tetanus-pertussis- containing vaccine (DTP1). The vast majority of these - live in low-income and middle- income countries. In addition, many children received their first dose of the measles-containing vaccine (MCV1) much later than scheduled, thus, are at significant risk of becoming infected before they are eventually vaccinated and may contribute to suboptimal herd immunity. In The Gambia, there is a recent upsurge of measles, with a 6-fold increase in cases as of mid-2022 compared to 2020 figures despite achieving a minimum MCV1coverage of 90% over the last decade. Recent data suggest that a large proportion of vaccinations are delayed or not delivered in an age-appropriate manner, according to the national vaccination windows. In addition, untimely MCV1 and zero-dose are thought to co-exist and clustered in certain remote communities and may contribute to suboptimal herd immunity. The PI, Dr Oghenebrume Wariri will apply novel spatiotemporal modelling approaches to map the subpopulation with untimely measles vaccination and zero- dose at fine-spatial scale and examine potential links with suboptimal herd immunity and risk of measles outbreaks. He will also examine how geographic accessibility shapes the uptake and delivery of routine vaccination in The Gambia. The project will leverage longitudinal cohort data from Health and Demographic Surveillance Systems in The Gambia, and bio-banked serological samples covering rural populations in the Kiang West District of The Gambia. There are four specific aims for this K43 award: 1) to determine the spatiotemporal pattern of untimely MCV1 and zero-dose children at high-spatial resolution in The Gambia; 2) to determine if there is a spatiotemporal relationship between cluster location of untimely MCV1 and measles population immunity in The Gambia; 3) To investigate the contribution of geographic accessibility (between households and vaccination posts; and between fixed and outreach vaccination posts) to zero-dose prevalence and delayed MCV1; 4) to model geographic access to routine vaccination services to understand the utility of the current vaccine delivery channels and potentially identify optimal locations of vaccination clinics and posts. This K43 Award will equip Dr Wariri with novel skills and competencies in geospatial and infectious disease modelling, manuscript and grant writing. Dr Wariri will be working with a multi-disciplinary mentoring committee comprising internationally-recognised African, UK, and US-based experts in vaccinology, population immunity and infectious diseases modelling, and geospatial modelling. The proposed research, in combination with a structured mentoring and training plan that includes didactic courses and workshops, is designed to facilitate Dr. -term goal of developing an independently funded infectious diseases and spatial epidemiology research program focussed on vaccination in Africa, consistent with the mission of the Fogarty International Centre.