1Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, Michigan.
2The Institute of Global Health Equity, University of Michigan, Ann Arbor, Michigan.
Am J Trop Med Hyg. 2021 May 17;105(1):245-253. doi: 10.4269/ajtmh.21-0006.
New vaccine introduction accompanied by social mobilization activities could contribute to improved routine immunization timeliness. This study assesses the impact of Kenya's introduction of pneumococcal conjugate vaccine (PCV) on the timeliness of routine childhood vaccination in two informal, urban settlements in Nairobi. Data collected from 2007 to 2015 as part of a demographic surveillance system were used to estimate annual vaccination delays of ≥ 4 weeks among children aged 12-23 months in the period before and after the introduction of PCV in Kenya. Binomial segmented regression models using generalized estimating equations examined the association between vaccine introduction and timeliness of routine immunization. Over half of all children vaccinated in the two urban areas received one or more doses ≥ 4 weeks after the recommended age. The timeliness of routine immunization showed slight improvements or nonsignificant changes during the years following PCV introduction compared with the preceding years (adjusted prevalence ratio [aPR]: 0.67, 95% CI: 0.45-0.99 for Bacille Calmette-Guerin receipt; aPR: 0.59, 95% CI: 0.41-0.83 for third dose Pentavalent receipt; aPR: 1.19, 95% CI: 0.99-1.42 for measles). However, as of 2015, delayed vaccination remained prevalent in children, particularly among the poorest residing in the settlements. Many sub-Saharan African countries have introduced new life-saving vaccines into their routine childhood immunization schedule. Additional evidence regarding the positive or neutral influence of new vaccine introduction on the performance of delivery systems provides further justification to sustain the inclusion of these more costly vaccines in the immunization schedule.
新疫苗的引入伴随着社会动员活动，可以促进常规免疫及时性的提高。本研究评估了肯尼亚引入肺炎球菌结合疫苗（PCV）对内罗毕两个非正规城市住区儿童常规疫苗接种及时性的影响。研究使用了 2007 年至 2015 年期间作为人口监测系统一部分收集的数据，以估计在肯尼亚引入 PCV 之前和之后，12-23 个月龄儿童每年接种疫苗的延迟时间超过 4 周的比例。使用广义估计方程的二项式分段回归模型，研究了疫苗引入与常规免疫及时性之间的关联。在两个城市地区接种的所有儿童中，超过一半的儿童在推荐年龄后 4 周或更长时间内接种了一剂或多剂疫苗。与引入 PCV 之前的年份相比，PCV 引入后的几年中，常规免疫的及时性略有改善或无显著变化（卡介苗接种的调整患病率比 [aPR]：0.67，95%CI：0.45-0.99；第五剂五联疫苗接种的 aPR：0.59，95%CI：0.41-0.83；麻疹接种的 aPR：1.19，95%CI：0.99-1.42）。然而，截至 2015 年，儿童中仍存在延迟接种疫苗的情况，特别是在住区中最贫困的儿童中。许多撒哈拉以南非洲国家已将新的救命疫苗纳入其常规儿童免疫接种计划。关于新疫苗引入对疫苗接种系统性能的积极或中性影响的更多证据进一步证明了维持将这些更昂贵的疫苗纳入免疫接种计划的合理性。
