Multiple variants of the virus that causes COVID-19 have been identified globally during the COVID-19 pandemic. Variants are determined by their genetic sequences. It's important to understand that genetic mutations of the virus that causes COVID-19, SARS-CoV-2, are expected, and that there are many strains of the virus.  Public health, academic, and clinical partners are working together to sequence the genetic material of the virus in California. The term variants being monitored (VBM) is used to describe a variant for which there are data indicating a potential or clear impact on treatment or that has been associated with more severe disease or increased transmission but are no longer detected or are circulating at very low levels, and as such, do not pose a significant and imminent risk to public. The term variant of interest (VOI) is used to describe a newly emerging variant for which the medical and public health importance is not yet known. If a variant is thought to be more contagious or likely to cause greater illness or severe disease, or may impact treatment or vaccine response, then it is considered a variant of concern (VOC).  

B.1.617.2 (Delta) variants are associated with approximately 200% increased transmission. May have moderately decreased response to antibody treatments. (Delta totals include all Delta AY sublineages).

Omicron (B.1.1.529) is a new SARS-CoV-2 variant that was designated as a Variant of Concern by the WHO on November 26, 2021. California reported its first case of Omicron variant on December 1, 2021. This was the first reported case of the Omicron variant in the United States.