Department of Biology, Virginia Commonwealth University, Richmond, VA, 23284-2012, USA.
Department of Mathematics and Applied Mathematics, Virginia Commonwealth University, Richmond, VA, 23284-2014, USA.
Bull Math Biol. 2020 Jun 15;82(6):80. doi: 10.1007/s11538-020-00748-5.
Hepatitis B (HepB) is one of the most common infectious diseases affecting over two billion people worldwide. About one third of all HepB cases are in China. In recent years, China made significant efforts to implement a nationwide HepB vaccination program and reduced the number of unvaccinated infants from 30 to 10%. However, many individuals still remain unprotected, particularly those born before 2003. Consequently, a catch-up retroactive vaccination is an important and potentially cost-effective way to reduce HepB prevalence. In this paper, we analyze a game theoretical model of HepB dynamics that incorporates government-provided vaccination at birth coupled with voluntary retroactive vaccinations. Given the uncertainty about the long-term efficacy of the HepB vaccinations, we study several scenarios. When the waning rate is relatively high, we show that this retroactive vaccination should be a necessary component of any HepB eradication effort. When the vaccine offers long-lasting protection, the voluntary retroactive vaccination brings the disease incidence to sufficiently low levels. Also, we find that the optimal vaccination rates are almost independent of the vaccination coverage at birth. Moreover, it is in an individual's self-interest to vaccinate (and potentially re-vaccinate) at a rate just slightly above the vaccine waning rate.
乙型肝炎（HepB）是全球影响超过 20 亿人的最常见传染病之一。全球三分之一的 HepB 病例在中国。近年来，中国大力实施全国性乙型肝炎疫苗接种计划，将未接种疫苗的婴儿数量从 30%减少到 10%。然而，仍有许多人未得到保护，尤其是那些 2003 年前出生的人。因此，进行补种性的回溯性疫苗接种是减少 HepB 流行率的重要且具有潜在成本效益的方法。在本文中，我们分析了一个包含政府提供的出生时疫苗接种和自愿回溯性疫苗接种的 HepB 动力学博弈理论模型。鉴于对 HepB 疫苗长期效果的不确定性，我们研究了几种情况。当衰减率较高时，我们表明这种回溯性疫苗接种应该是 HepB 根除努力的必要组成部分。当疫苗提供持久保护时，自愿回溯性疫苗接种会将疾病发病率降低到足够低的水平。此外，我们发现最佳疫苗接种率几乎与出生时的疫苗接种覆盖率无关。而且，个人出于自身利益考虑，以略高于疫苗衰减率的速度接种（并可能再次接种）疫苗。
