Granat Simo M, Ollgren Jukka, Herva Elja, Mia Zakaria, Auranen Kari, Mäkelä P Helena
National Public Health Institute, Department of Vaccines, Helsinki, Finland.
J Infect Dis. 2009 Jul 1;200(1):99-106. doi: 10.1086/599364.
Asymptomatic nasopharyngeal carriage is the main reservoir for transmission of Streptococcus pneumoniae. The rate of both carriage and pneumococcal disease decreases with age. To what extent these changes are the result of developing natural immunity is currently a subject of debate.
To study the hypothesis that previous carriage induces serotype-independent protective immunity to new colonization.
We compared the rates of pneumococcal acquisition for children with different previous carriage histories. We identified 435 episodes of carriage during the first year of life in follow-up data for 99 Bangladeshi children. Cox regression analysis was adjusted for serotype-specific exposure within the family and other confounding factors.
Previous pneumococcal carriage was associated with serotype-independent protection from subsequent acquisition (hazard ratio, 0.60 [95% confidence interval, 0.39-0.90]), whereas recent serotype-specific exposure within the family was associated with an 8-fold increase in the rate of acquisition for that serotype.
Our findings are consistent with the hypothesis that serotype-independent protective immunity is stimulated in young children by previous pneumococcal carriage and reduces the rate of new colonization. This immunity has the potential to modulate the development of carriage, irrespective of the colonizing serotype, and to do so starting early in infancy.
无症状鼻咽部携带是肺炎链球菌传播的主要储存库。携带率和肺炎球菌疾病发病率均随年龄增长而降低。这些变化在多大程度上是自然免疫发展的结果，目前仍是一个争论的话题。
研究既往携带会诱导对新定植产生血清型非依赖性保护性免疫这一假说。
我们比较了具有不同既往携带史的儿童的肺炎球菌获得率。在99名孟加拉国儿童的随访数据中，我们确定了出生后第一年的435次携带事件。Cox回归分析针对家庭内血清型特异性暴露和其他混杂因素进行了校正。
既往肺炎球菌携带与对后续获得的血清型非依赖性保护相关（风险比，0.60 [95%置信区间，0.39 - 0.90]），而近期家庭内血清型特异性暴露与该血清型获得率增加8倍相关。
我们的研究结果与以下假说一致，即既往肺炎球菌携带会刺激幼儿产生血清型非依赖性保护性免疫，并降低新定植率。这种免疫有可能调节携带的发展，无论定植血清型如何，并且在婴儿期早期就开始发挥作用。
