Respiratory Diseases Branch, Division of Bacterial Diseases, Centers for Disease Control and Prevention, 1600 Clifton Road, N.E. Atlanta, GA 30333, United States; Division of Global Health Protection, Centers for Disease Control and Prevention, PO Box 606-00621, Village Market, Nairobi, Kenya.
Centre for Global Health Research, Kenya Medical Research Institute, P.O. Box: 1578 - 40100, Kisumu, Kenya.
Vaccine. 2024 Nov 14;42(25):126120. doi: 10.1016/j.vaccine.2024.07.021. Epub 2024 Aug 14.
Kenya introduced Synflorix™ (GlaxoSmithKline, PCV10-GSK), a 10-valent pneumococcal conjugate vaccine, in 2011, using three primary doses and, in select areas, catch-up campaigns. Surveys conducted 1-2 years post-introduction showed a stable prevalence of pneumococcal colonization, with declines in vaccine-type carriage. However, little is known about the long-term impact of PCV10-GSK in Kenya.
We conducted a cross-sectional survey of pneumococcal carriage among children aged <5 years in November-December 2017 in Kibera (Nairobi informal settlement, no catch-up) and Asembo (rural western Kenya, 2-dose catch-up for children 1-4 years), using the same methods and settings as prior annual surveys from 2009 to 2013. Participants were randomly selected from an ongoing population-based surveillance platform. Nasopharyngeal swabs were frozen in skim milk-tryptone-glucose-glycerin media within 4 h and underwent culture with broth enrichment for pneumococcus. Isolates were serotyped by polymerase chain reaction and Quellung.
We enrolled 504 children, including 252 from each site; >90 % of participants had received 3 doses of PCV10-GSK. Pneumococcal colonization was detected in 210 (83.3 %) participants in Kibera and 149 (59.1 %) in Asembo, which was significantly lower than the prevalence observed in 2013 (92.9 % and 85.7 %, respectively). PCV10-GSK serotypes were detected in 35/252 (13.9 %) participants in Kibera and 23/252 (9.1 %) in Asembo, respectively; these prevalences were lower, but not statistically different, from vaccine-type carriage prevalences in 2013 (17.3 % and 13.3 %, respectively). In 2017 in both sites, serotypes 3, 6A, 19A, 19F, and 35B were among the most common serotypes.
Six years post-PCV10-GSK introduction, the prevalence of pneumococcal carriage among children has decreased, and the impact of PCV10-GSK on vaccine-type carriage has plateaued. Kenya recently changed from PCV10-GSK to Pneumosil™ (Serum Institute of India), a 10-valent PCV that includes serotypes 6A and 19A; these data provide historical context for interpreting changes in vaccine-type carriage following the PCV formulation switch.
肯尼亚于 2011 年引入了 10 价肺炎球菌结合疫苗 Synflorix（葛兰素史克，PCV10-GSK），使用了三剂基础免疫和在特定地区开展补种运动。接种后 1-2 年的调查显示，肺炎球菌定植的流行率保持稳定，疫苗型别携带率有所下降。然而，关于肯尼亚 PCV10-GSK 的长期影响知之甚少。
我们于 2017 年 11 月至 12 月在基贝拉（内罗毕非正规住区，无补种）和阿塞博（肯尼亚西部农村，2 剂补种 1-4 岁儿童）进行了一项小于 5 岁儿童肺炎球菌携带情况的横断面调查，使用了与 2009 年至 2013 年年度调查相同的方法和环境。参与者是从正在进行的基于人群的监测平台中随机选择的。鼻咽拭子在 4 小时内用脱脂牛奶-胰酶-葡萄糖-甘油培养基冷冻，并在肉汤中进行肺炎球菌富集培养。通过聚合酶链反应和胶乳试验对分离株进行血清型分型。
我们共纳入了 504 名儿童，其中基贝拉和阿塞博各 252 名；超过 90%的参与者已接受 3 剂 PCV10-GSK 接种。在基贝拉 252 名参与者中有 210 名（83.3%）和在阿塞博 252 名参与者中有 149 名（59.1%）检测到肺炎球菌定植，这明显低于 2013 年观察到的流行率（分别为 92.9%和 85.7%）。在基贝拉的 252 名参与者中有 35 名（13.9%）和在阿塞博的 252 名参与者中有 23 名（9.1%）检测到 PCV10-GSK 血清型；这些流行率虽有所下降，但与 2013 年疫苗型别携带率（分别为 17.3%和 13.3%）相比，差异无统计学意义。在 2017 年两个地点，血清型 3、6A、19A、19F 和 35B 是最常见的血清型。
在 PCV10-GSK 引入 6 年后，儿童肺炎球菌携带率下降，PCV10-GSK 对疫苗型别携带的影响已趋于平稳。肯尼亚最近已将疫苗由 PCV10-GSK 转换为 Pneumosil（印度血清研究所），这是一种包含血清型 6A 和 19A 的 10 价 PCV；这些数据为解释疫苗配方转换后疫苗型别携带率的变化提供了历史背景。
