A mathematical model of serotype replacement in pneumococcal carriage following vaccination
A mathematical model of serotype replacement in pneumococcal carriage following vaccination
复制标题
DOI：
10.1098/rsif.2013.0786
复制
发表时间：
2013-12-06
影响因子：
3.9
通讯作者：
Isham, Valerie
中科院分区：
文献类型：
--
作者：
Bottomley, Christian;Roca, Anna;Isham, Valerie
一些儿童疫苗接种方案最近引进了肺炎链球菌的疫苗接种，肺炎球菌是肺炎和脑膜炎的主要原因。目前使用的肺炎球菌结合疫苗（PCV）仅能预防某些血清型的细菌，现在有强有力的证据表明，疫苗中不包括的那些血清型在大多数接种人群中的流行率增加。本文提出了一个描述猪鼻吸湿运动的数学模型。肺炎，允许携带多种血清型。该模型用于预测PCV引入后疫苗型（VT）和非VT（NVT）血清型的流行率。使用冈比亚的疫苗接种前数据，通过最大似然法获得模型的参数估计值。该模型预测，低（1，6A和9V）和中等（4，5，7F，14，18C，19A和19F）流行血清型可以通过疫苗接种消除，但由于NVT血清型流行率的增加，总体携带率仅略有下降。血清型替换将是连续的，最初以高和中等流行率的NVT血清型为主，随后增加低流行率的血清型。我们研究了一种假设的疫苗的影响，该疫苗提供对所有血清型的部分保护，并发现这降低了总体携带率，但无法消除低或中等流行率的血清型。
A number of childhood vaccination programmes have recently introduced vaccination against Streptococcus pneumoniae, the pneumococcus, a major cause of pneumonia and meningitis. The pneumococcal conjugate vaccines (PCVs) that are currently in use only protect against some serotypes of the bacterium, and there is now strong evidence that those serotypes not included in the vaccine increase in prevalence among most vaccinated populations. We present a mathematical model for the dynamics of nasopharyngeal carriage of S. pneumoniae that allows for carriage with multiple serotypes. The model is used to predict the prevalence of vaccine type (VT) and non-VT (NVT) serotypes following the introduction of PCV. Parameter estimates for the model are obtained by maximum likelihood using prevaccination data from The Gambia. The model predicts that low (1, 6A and 9V) and medium (4, 5, 7F, 14, 18C, 19A and 19F) prevalence serotypes can be eliminated through vaccination, but that the overall prevalence of carriage will be reduced only slightly because of an increase in the prevalence of NVT serotypes. Serotype replacement will be sequential, with high and medium prevalence NVT serotypes dominating initially, followed by an increase of serotypes of low prevalence. We examine the impact of a hypothetical vaccine that provides partial protection against all serotypes, and find that this reduces overall carriage, but is unable to eliminate low or medium prevalence serotypes.