Predicting vaccine effectiveness in livestock populations: A theoretical framework applied to PRRS virus infections in pigs
Predicting vaccine effectiveness in livestock populations: A theoretical framework applied to PRRS virus infections in pigs
复制标题
DOI：
10.1371/journal.pone.0220738
复制
发表时间：
2019-08-30
期刊：
影响因子：
3.7
通讯作者：
Doeschl-Wilson, Andrea
中科院分区：
文献类型：
--
作者：
Bitsouni, Vasiliki;Lycett, Samantha;Doeschl-Wilson, Andrea
疫苗仍然是控制家畜传染病的主要工具之一。尽管市场上有大量的兽医疫苗，并经常用于保护动物免受特定病原体的感染，但所述疾病往往继续存在，有时发病率很高。某些疫苗在实地的有效性有限，这给有效疫苗应具备的必要特性以及实现疫苗接种计划预期目标的最有效疫苗接种策略留下了悬而未决的问题。到目前为止，缺乏一种系统的方法来研究不同类型的疫苗和疫苗接种策略的综合效果。在本文中，我们开发了一个理论框架，用于模拟疫苗接种的流行病学后果与不完善的疫苗的各种类型，管理使用不同的策略，以不同的替代率和异质性的疫苗反应性的牛群。将该模型应用于猪繁殖与呼吸综合征（PRRS），尽管常规疫苗接种仍然是全球最重要的地方性猪病之一，然后我们研究了这些不同因素单独和组合对猪群内病毒传播的影响。我们推导出在不完美的疫苗诱导有限的灭菌免疫的情况下，防止感染入侵的阈值条件。本研究中开发的模型不仅对PRRS，而且对主要通过直接接触传播的其他病毒感染的疫苗和疫苗接种计划的开发具有实际意义。
Vaccines remain one of the main tools to control infectious diseases in domestic livestock. Although a plethora of veterinary vaccines are on the market and routinely applied to protect animals against infection with particular pathogens, the disease in question often continues to persist, sometimes at high prevalence. The limited effectiveness of certain vaccines in the field leaves open questions regarding the required properties that an effective vaccine should have, as well as the most efficient vaccination strategy for achieving the intended goal of vaccination programmes. To date a systematic approach for studying the combined effects of different types of vaccines and vaccination strategies is lacking. In this paper, we develop a theoretical framework for modelling the epidemiological consequences of vaccination with imperfect vaccines of various types, administered using different strategies to herds with different replacement rates and heterogeneity in vaccine responsiveness. Applying the model to the Porcine Reproductive and Respiratory Syndrome (PRRS), which despite routine vaccination remains one of the most significant endemic swine diseases worldwide, we then examine the influence of these diverse factors alone and in combination, on within-herd virus transmission. We derive threshold conditions for preventing infection invasion in the case of imperfect vaccines inducing limited sterilizing immunity. The model developed in this study has practical implications for the development of vaccines and vaccination programmes in livestock populations not only for PRRS, but also for other viral infections primarily transmitted by direct contact.