Figure 1.
Serum sampling schedules in 6 phase 3 coronavirus disease 2019 vaccine trials. The sampling time points are measured from the day of enrollment.
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.