Variants and Genomic Surveillance for SARS-CoV-2

Updated Apr. 26, 2023

Variants and Hospitalizations

CDC is monitoring current COVID-19 cases. Learn more about variants and their expected impact on hospitalizations.

About Variants Hospitalization Forecast

female lab technician doing research with a microscope in the lab - coronavirus

Genomic Surveillance

Classifications and Definitions
Variants of the Virus
About Genomic Surveillance

Data & Sequencing

Variant Proportions in the US
Global Variant Data
Sequencing for SARS-CoV-2 (SPHERES)
Published COVID-19 Sequences

About Variants

Many viruses are constantly changing, including the virus that causes COVID-19. These changes occur over time and can lead to the emergence of variants that may have new characteristics, including different ways of spreading.

Research and Selected Publications

MMWR: Spike Gene Target Amplification in a Diagnostic Assay as a Marker for Public Health Monitoring of Emerging SARS-CoV-2 Variants — United States, November 2021–January 2023
MMWR: Genomic Surveillance for SARS-CoV-2 Variants: Predominance of the Delta (B.1.617.2) and Omicron (B.1.1.529) Variants — United States, June 2021–January 2022
MMWR: Genomic Surveillance for SARS-CoV-2 Variants Circulating in the United States, December 2020–May 2021