Acosta-Alonzo Carmen B, Erovenko Igor V, Lancaster Aaleah, Oh Hyunju, Rychtář Jan, Taylor Dewey
Department of Mathematics and Computer Science, Bennett College, Greensboro, NC 27401, USA.
Department of Mathematics and Statistics, University of North Carolina at Greensboro, Greensboro, NC 27402, USA.
Proc Math Phys Eng Sci. 2020 Sep;476(2241):20200354. doi: 10.1098/rspa.2020.0354. Epub 2020 Sep 2.
Typhoid fever has long established itself endemically in rural Ghana despite the availability of cheap and effective vaccines. We used a game-theoretic model to investigate whether the low vaccination coverage in Ghana could be attributed to rational human behaviour. We adopted a version of an epidemiological model of typhoid fever dynamics, which accounted not only for chronic life-long carriers but also for a short-cycle transmission in the immediate environment and a long-cycle transmission via contamination of the water supply. We calibrated the model parameters based on the known incidence data. We found that unless the (perceived) cost of vaccination is negligible, the individually optimal population vaccination rate falls significantly short of the societally optimal population vaccination rate needed to reach herd immunity. We expressed both the herd immunity and the optimal equilibrium vaccination rates in terms of only a few observable parameters such as the incidence rate, demographics, vaccine waning rate and the perceived cost of vaccination relative to the cost of infection. This allowed us not to rely on other uncertain epidemiological model parameters and, in particular, to bypass uncertainties about the role of the carriers in the transmission.
尽管有价格低廉且有效的疫苗，但伤寒热在加纳农村地区长期呈地方流行状态。我们使用博弈论模型来研究加纳疫苗接种覆盖率低是否可归因于人类的理性行为。我们采用了一个伤寒热动态流行病学模型版本，该模型不仅考虑了慢性终身携带者，还考虑了在直接环境中的短周期传播以及通过供水污染的长周期传播。我们根据已知的发病率数据对模型参数进行了校准。我们发现，除非疫苗接种（感知到的）成本可忽略不计，否则个体最优的群体疫苗接种率会显著低于达到群体免疫所需的社会最优群体疫苗接种率。我们仅根据少数可观测参数（如发病率、人口统计学、疫苗衰减率以及相对于感染成本的疫苗接种感知成本）来表示群体免疫和最优均衡疫苗接种率。这使我们无需依赖其他不确定的流行病学模型参数，尤其是绕过了关于携带者在传播中作用的不确定性。
