Wittgenstein Centre for Demography and Global Human Capital (IIASA, OeAW, University of Vienna), Vienna Institute of Demography at the Austrian Academy of Sciences, Vordere Zollamtsstraße 3, 1030, Vienna, Austria.
Wittgenstein Centre for Demography and Global Human Capital (IIASA, OeAW, University of Vienna), Vienna Institute of Demography at the Austrian Academy of Sciences, Vordere Zollamtsstraße 3, 1030, Vienna, Austria; International Institute for Applied Systems Analysis, Schlossplatz 1, A-2361 Laxenburg, Austria.
Int J Infect Dis. 2022 Jun;119:178-183. doi: 10.1016/j.ijid.2022.03.059. Epub 2022 Apr 6.
This study aimed to test the behavior of the case fatality rate (CFR) in a mixed population of vaccinated and unvaccinated individuals by illustrating the role of both the effectiveness of vaccines in preventing deaths and the detection of infections among both the vaccinated (breakthrough infections) and unvaccinated individuals.
We simulated three hypothetical CFR scenarios that resulted from a different combination of vaccine effectiveness in preventing deaths and the efforts in detecting infections among both the vaccinated and unvaccinated individuals.
In the presence of vaccines, the CFR depends not only on the effectiveness of vaccines in preventing deaths but also on the detection of breakthrough infections. As a result, a decline in the CFR may not imply that vaccines are effective in reducing deaths. Likewise, a constant CFR can still mean that vaccines are effective in reducing deaths.
Unless vaccinated people are also tested for COVID-19 infection, the CFR loses its meaning in tracking the pandemic. This shows that unless efforts are directed at detecting breakthrough infections, it is hard to disentangle the effect of vaccines in reducing deaths from the probability of detecting infections on the CFR.
本研究旨在通过说明疫苗在预防死亡方面的有效性以及在接种疫苗者（突破性感染）和未接种疫苗者中检测感染的作用，检验混合接种疫苗和未接种疫苗人群中病死率（CFR）的变化情况。
我们模拟了三种假设的 CFR 情景，这些情景源自疫苗在预防死亡方面的有效性以及在接种疫苗者和未接种疫苗者中检测感染的努力程度的不同组合。
在存在疫苗的情况下，CFR 不仅取决于疫苗在预防死亡方面的有效性，还取决于突破性感染的检测情况。因此，CFR 的下降并不一定意味着疫苗能有效降低死亡人数。同样，CFR 保持不变仍可能意味着疫苗能有效降低死亡人数。
除非对接种疫苗的人进行 COVID-19 感染检测，否则 CFR 在跟踪大流行方面就失去了意义。这表明，除非将努力方向转向检测突破性感染，否则很难将疫苗在降低死亡率方面的效果与 CFR 上检测感染的概率区分开来。
