Estimation of Waning Vaccine Efficacy
疫苗保护效力随时间衰减的估计
Whether the protection afforded by a vaccine wanes over time and if so, by how much, are important public health questions with implications for mass immunization programs. However, the measurement of such effects is fraught with difficulties. Generally, clinical trials are too short to provide evidence on waning effects. Thus it is necessary to rely on epidemiologic data, which are subject to ascertainment bias. Furthermore, standard epidemiologic measures, such as hazard…