New England Journal of Medicine
March 26, 2020 Vol. 382 No. 13
http://www.nejm.org/toc/nejm/medical-journal

Perspective
Defining the Epidemiology of Covid-19 — Studies Needed
Marc Lipsitch, D.Phil., David L. Swerdlow, M.D., and Lyn Finelli, Dr.P.H.