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.
The estimated household secondary attack rates among ≤17- (hollow circle) and ≥18- (solid circle) year-old individuals for each case definition (Table 1). The labeled short horizontal lines denote the point estimate, and the solid vertical lines capped with symbols denote the 95% confidence intervals. The solid gray horizontal line denotes a null secondary attack rate of 0%.
