Early detection of SARS-CoV-2 variants using traveler-based genomic surveillance at four US airports, September 2021- January 2022.

We enrolled arriving international air travelers in SARS-CoV-2 genomic surveillance, using molecular testing of pooled nasal swabs, and sequencing positive samples for viral sublineage. Traveler-based genomic surveillance provided early warning variant detection; we reported the first U.S. Omicron BA.2 and first BA.3 in North America, weeks before next reported detection.