Institute for Disease Modeling, 3150 139th Ave SE, Bellevue, WA 98005, USA.
Institute for Disease Modeling, 3150 139th Ave SE, Bellevue, WA 98005, USA.
Vaccine. 2019 Sep 24;37(41):6039-6047. doi: 10.1016/j.vaccine.2019.08.050. Epub 2019 Aug 27.
Measles causes significant childhood morbidity in Nigeria. Routine immunization (RI) coverage is around 40% country-wide, with very high levels of spatial heterogeneity (3-86%), with supplemental immunization activities (SIAs) at 2-year or 3-year intervals. We investigated cost savings and burden reduction that could be achieved by adjusting the inter-campaign interval by region.
We modeled 81 scenarios; permuting SIA calendars of every one, two, or three years in each of four regions of Nigeria (North-west, North-central, North-east, and South). We used an agent-based disease transmission model to estimate the number of measles cases and ingredients-based cost models to estimate RI and SIA costs for each scenario over a 10 year period.
Decreasing SIAs to every three years in the North-central and South (regions of above national-average RI coverage) while increasing to every year in either the North-east or North-west (regions of below national-average RI coverage) would avert measles cases (0.4 or 1.4 million, respectively), and save vaccination costs (save $19.4 or $5.4 million, respectively), compared to a base-case of national SIAs every two years. Decreasing SIA frequency to every three years in the South while increasing to every year in the just the North-west, or in all Northern regions would prevent more cases (2.1 or 5.0 million, respectively), but would increase vaccination costs (add $3.5 million or $34.6 million, respectively), for $1.65 or $6.99 per case averted, respectively.
Our modeling shows how increasing SIA frequency in Northern regions, where RI is low and birth rates are high, while decreasing frequency in the South of Nigeria would reduce the number of measles cases with relatively little or no increase in vaccination costs. A national vaccination strategy that incorporates regional SIA targeting in contexts with a high level of sub-national variation would lead to improved health outcomes and/or lower costs.
麻疹在尼日利亚导致大量儿童发病。全国常规免疫（RI）覆盖率约为 40%，空间异质性非常高（3-86%），每两年或三年进行一次补充免疫活动（SIA）。我们研究了通过按地区调整运动间隔可以实现的成本节约和负担减轻。
我们模拟了 81 种情况；在尼日利亚的四个地区（西北、中北部、东北部和南部）中，每年、每两年或每三年改变一次 SIA 日历。我们使用基于代理的疾病传播模型来估计每种情况下麻疹病例的数量，并使用基于成分的 RI 和 SIA 成本模型来估计每种情况下 10 年内的 RI 和 SIA 成本。
在中北部和南部（RI 覆盖率高于全国平均水平的地区），将 SIA 减少到每三年一次，而在东北部或西北部（RI 覆盖率低于全国平均水平的地区）增加到每年一次，将避免麻疹病例（分别为 0.4 或 1.4 百万人），并节省疫苗接种成本（分别节省 1940 万美元或 5400 万美元），与全国每两年进行一次 SIA 的基础案例相比。在南部，将 SIA 频率减少到每三年一次，同时在西北部或所有北部地区增加到每年一次，可以预防更多的病例（分别为 210 万或 500 万），但会增加疫苗接种成本（分别增加 350 万美元或 3.46 亿美元），每例病例的成本分别为 1.65 美元或 6.99 美元。
我们的模型表明，在 RI 较低且出生率较高的北部地区增加 SIA 频率，同时在尼日利亚南部降低频率，可以减少麻疹病例的数量，而相对较少或没有增加疫苗接种成本。在具有高度国家以下一级差异的情况下，将国家免疫战略纳入区域 SIA 目标制定，将改善卫生结果和/或降低成本。
