The BMJ is targeted towards healthcare professionals, students, and medically-interested lay-people and usually requires a subscription. However, it’s made it content about the virus available for free.
The U.S. Centers for Disease Control is a national agency on the frontlines of the current pandemic that is coordinating expert advice from medical and public health professionals and advising healthcare works on dealing with the crisis. It also has helpful information for the public.
The World Health Organization is an international agency on the frontline of the current pandemic that is coordinating expert advice from medical and public health professionals and advising national health agencies dealing with the crisis. It also has helpful information for the public.
The GPO's GovernmentBookTalk website has compiled links to information on the coronavirus pandemic from various government agencies. (The Government Publishing Office has as its mission to serve as official, digital, and secure source for producing, preserving, and distributing official Federal Government publications and information products for Congress, Federal agencies, and the American public.)