Fig. 2.
Relative self-reported frequency in the last 12 months of a upper respiratory tract and b gastrointestinal tract infections according to the three groups of self-assessed infection vulnerability
Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.