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.
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) lineages responsible for the first SARS-CoV-2 infectious episode and corresponding SARS-CoV-2 lineages responsible for the second infection. Different lineages, identified by whole-genome sequencing, are represented by different tones; the width of the linkages is proportional to the number of people infected with each SARS-CoV-2 lineage.
