Target Trial Emulation to Study the Effects of COVID-19 Vaccine During Pregnancy

Department of Epidemiology Seminar Series

Speaker:

Sonia Hernández-Díaz, MD, DrPH
Professor of Epidemiology, Department of Epidemiology
Harvard T.H. Chan School of Public Health

Description: Questions on the comparative effectiveness or safety of treatments and vaccines during pregnancy are often answered using observational data. Causal inference from observational data can be conceptualized as an attempt to emulate a hypothetical pragmatic randomized trial: the target trial.  In this seminar we will propose a protocol framework that makes the target trial explicit. Emulating a trial forces the investigators to specify the causal question, the study population and eligibility criteria, the exposure and reference groups, and start and end of follow-up. In addition, investigators must consider which assumptions are necessary for specific analyses. This process itself can be enlightening and can help describe and avoid biases including confounding, immortal person time bias, and prevalent user bias. We will discuss applications to different causal questions in the setting of treatment decisions before, early and late in pregnancy.