Viruses mutate over time, and as a result, new variants of viruses tend to emerge. Most mutations do not produce clinically relevant changes but occasionally mutations occur that may be beneficial for the virus.
Multiple variants of SARS-CoV-2, the virus that causes COVID-19, have emerged or spread throughout different parts of the world, including the United States. Variant viruses may carry mutations that could be associated with differences in diagnostic test performance, changes in disease epidemiology, clinical outcomes, and effectiveness of certain therapeutics or vaccines.
For timely information on emerging variants and vaccine efficacy, refer to our COVID-19 Vaccines FAQ.