This symposium reviews epidemiologic methods currently used to describe, predict, and investigate the causes of health outcomes in humans. Ideas from screening as well as from infectious disease modeling and their relevance during the COVID-19 pandemic are discussed. With the randomized clinical trial as a paradigm, the symposium examines common problems in the design, analysis, and interpretation of observational studies on the effectiveness and safety of vaccines and treatments for COVID-19. Problems of population definition, exposure and disease specifications, confounding, and misclassification are considered in the light of data sources typically available.

Course Objectives:
• Review the fundamentals of epidemiologic study designs for description, prediction
and causal inference.
• Recognize the peculiarities of study designs for infectious diseases research.
• Judge the information presented in scientific papers and draw valid conclusions.
• Consolidate previous knowledge to develop a study design proposal for a current relevant topic.
• Provide constructive comments and discuss manuscripts and study proposals.