感染后的流行病学影响死亡率

Epidemiological Impacts of Post-Infection Mortality

传染病可能对其宿主造成一些长期损害,即使在康复后也会导致死亡率升高。所谓的“长期新冠肺炎”并发症导致的死亡率清楚地说明了这一潜力,但这种感染后死亡率(PIM)对流行病动态的影响是未知的。使用包含PIM的流行病学模型,我们检查这种影响的重要性。发现与感染期间的死亡率相反,PIM可以诱导流行循环。这种影响是由于死亡率升高和通过以前感染的易感人群再次感染之间的相互影响。特别是,强大的免疫力(通过降低再感染的易感性)降低了循环的可能性;另一方面,疾病引起的死亡率可与弱PIM相互作用产生周期性。在没有PIM的情况下,我们证明了独特的地方性均衡是稳定的,因此我们的关键结果是PIM是一个被忽视的现象,可能会破坏稳定。总的来说,考虑到潜在的广泛影响,我们的发现强调了特征化的重要性,易感性的异质性(通过PIM和宿主免疫的稳健性)用于准确的流行病学预测。特别是对于没有强大免疫力的疾病,如SARS-CoV-2 (严重急性呼吸系统综合征冠状病毒2型),PIM可能是复杂流行病学动态的基础,特别是在季节变换的情况下。

Infectious diseases may cause some long-term damage to their host, leading to elevated mortality even after recovery. Mortality due to complications from so-called “long COVID” is a stark illustra-tion of this potential, but the impacts of such post-infection mortality (PIM) on epidemic dynamics are not known. Using an epidemiological model that incorporates PIM, we examine the importance of this effect. We find that in contrast to mortality during infection, PIM can induce epidemic cycling. The effect is due to interference between elevated mortality and reinfection through the previously infected susceptible pool. In particular, robust immunity (via decreased susceptibility to reinfection) reduces the likelihood of cycling;on the other hand, disease-induced mortality can interact with weak PIM to generate periodicity. In the absence of PIM, we prove that the unique endemic equilib-rium is stable and therefore our key result is that PIM is an overlooked phenomenon that is likely to be destabilizing. Overall, given potentially widespread effects, our findings highlight the importance of characterizing heterogeneity in susceptibility (via both PIM and robustness of host immunity) for accurate epidemiological predictions. In particular, for diseases without robust immunity, such as SARS-CoV-2, PIM may underlie complex epidemiological dynamics especially in the context of sea-sonal forcing.