An official website of the United States government
The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before
sharing sensitive information, make sure you’re on a federal
government site.
The site is secure.
The https:// ensures that you are connecting to the
official website and that any information you provide is encrypted
and transmitted securely.
Mackenzie I, Rous P.Mackenzie I, et al. Among authors: rous p.J Exp Med. 1941 Feb 28;73(3):391-416. doi: 10.1084/jem.73.3.391.J Exp Med. 1941.PMID: 19871085Free PMC article.