Briefly describe the research object of immigration epidemiology

Immigration epidemiology: It distinguishes the role of genetic factors and environmental factors by observing the differences of disease incidence and mortality among immigrants, local residents in immigrant countries and people in their original places, and explores the clues of etiology from the differences. 、

The target should be: immigrants, local residents of immigrant countries and people in their original places of residence.

Immigrant epidemiological research cannot be sampled.