Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, United States.
Department of Biostatistics, Yale School of Public Health, New Haven, CT, United States.
Vaccine. 2020 Nov 17;38(49):7756-7763. doi: 10.1016/j.vaccine.2020.10.045. Epub 2020 Oct 22.
Streptococcus pneumoniae remains a leading cause of morbidity and mortality. Pneumococcal conjugate vaccines (PCVs) are effective but target only a fraction of the more than 90 pneumococcal serotypes. As a result, the introduction of PCVs has been followed by the emergence of non-vaccine serotypes. With higher-valency PCVs currently under development, there is a need to understand and predict patterns of serotype replacement to anticipate future changes.
In this study, we fit a hierarchical Bayesian regression model to evaluate patterns of change in serotype prevalence post-PCV introduction in Israel from 2009 to 2016.
We found that the assumption that non-vaccine serotypes increase by the same proportion overestimates changes in serotype prevalence in Jewish and Bedouin children. Furthermore, pre-vaccine prevalence was positively associated with increases in prevalence over the study period. From our analyses, serotypes 12F, 8, 16F, 33F, 9N, 7B, 10A, 22F, 24F, and 17F were estimated to have gained the most cases of invasive pneumococcal disease through serotype replacement in the Jewish population. However, this model also failed to quantify some additional cases gained, suggesting that changes in carriage in children alone may be insufficient to explain serotype replacement in disease.
Understanding of serotype replacement is important as higher-valency vaccines are introduced.
肺炎链球菌仍然是发病率和死亡率的主要原因。肺炎球菌结合疫苗（PCV）是有效的，但仅针对超过 90 种肺炎球菌血清型中的一部分。因此，在引入 PCV 之后，出现了非疫苗血清型。随着更高价 PCV 的开发，有必要了解和预测血清型替代模式，以预测未来的变化。
在这项研究中，我们拟合了一个分层贝叶斯回归模型，以评估 2009 年至 2016 年期间以色列引入 PCV 后血清型流行率变化的模式。
我们发现，假设非疫苗血清型按相同比例增加，会高估犹太人和贝都因人儿童中血清型流行率的变化。此外，疫苗接种前的流行率与研究期间流行率的增加呈正相关。根据我们的分析，血清型 12F、8、16F、33F、9N、7B、10A、22F、24F 和 17F 被估计在犹太人群体中通过血清型替代获得了最多的侵袭性肺炎球菌疾病病例。然而，该模型也未能量化一些额外的获得病例，这表明儿童携带率的变化可能不足以解释疾病中的血清型替代。
随着更高价疫苗的引入，对血清型替代的理解非常重要。
