Biosecurity Program, Kirby Institute, Faculty of Medicine, The University of New South Wales, Sydney, Australia.
College of Public Service and Community Solutions, Arizona State University, Arizona, USA.
Hum Vaccin Immunother. 2021 Mar 4;17(3):738-746. doi: 10.1080/21645515.2020.1800324. Epub 2020 Dec 2.
The reemergence of smallpox as a bioterrorism attack is now an increasing and legitimate concern. Advances in synthetic biology have now made it possible for the virus to be synthesized in a laboratory, with methods publicly available. Smallpox introduction into a susceptible population, with increased immunosuppression and an aging population, raises questions of how vaccination should be used in an epidemic situation when supply may be limited. We constructed three modified susceptible-latent-infectious-recovered (SEIR) models to simulate targeted, ring and mass vaccination in response to a smallpox outbreak in Sydney, Australia. We used age-specific distributions of susceptibility, infectivity, contact rates, and tested outputs under different assumptions. The number of doses needed of second- and third-generation vaccines are estimated, along with the total number of deaths at the end of the epidemic. We found a faster response is the key and ring vaccination of traced contacts is the most effective strategy and requires a smaller number of doses. However if public health authorities are unable to trace a high proportion of contacts, mass vaccination with at least 125,000 doses delivered per day is required. This study informs a better preparedness and response planning for vaccination in a case of a smallpox outbreak in a setting such as Sydney.
天花作为生物恐怖袭击的重现，现在是一个日益令人担忧的合理问题。合成生物学的进步现在使得在实验室中合成病毒成为可能，而且方法是公开的。天花被引入易感人群，加上免疫抑制增加和人口老龄化，引发了在供应可能有限的情况下，应该如何在流行疫情中使用疫苗的问题。我们构建了三个改良的易感-潜伏-感染-恢复（SEIR）模型，以模拟针对澳大利亚悉尼爆发天花的靶向、环式和大规模疫苗接种。我们使用了特定年龄的易感性、传染性、接触率分布，并根据不同的假设进行了测试。我们估计了第二和第三代疫苗所需的剂量数，以及流行疫情结束时的总死亡人数。我们发现更快的响应是关键，追踪接触者的环式疫苗接种是最有效的策略，所需的剂量较少。然而，如果公共卫生当局无法追踪到很大比例的接触者，则需要每天至少接种 12.5 万剂的大规模疫苗接种。本研究为在类似悉尼的环境中发生天花爆发时的疫苗接种做好了更好的准备和应对规划。
