https://www.cdc.gov/coronavirus/2019-ncov/covid-data/covidview/index.html
The virus that causes COVID-19 is constantly changing through mutation, leading to new variants, including ones classified as variants of concern (VOCs). VOCs have the potential to spread more easily and quickly than other variants, which could lead to more cases of COVID-19. A recent CDC study found that the circulation of SARS-CoV-2 variants in the United States changed rapidly from December 2020 to May 2021, demonstrating how quickly a new variant can emerge, spread, and become the dominant strain.
Currently, several variants are found around the world, including in the United States. On June 15, 2021, the B.1.617.2 (Delta)* variant was classified as a VOC because it spreads from person to person more easily than other variants and may cause more severe disease. B.1.617.2 has been reported in 77 countries and in the United Kingdom has become the main variant in COVID-19 cases. In the United States, the proportion** of B.1.617.2 for the 2-week period ending June 19, 2021, is predicted to increase to 20.6% nationally and be higher in regions 2, 6, 7, 8, and 9.
The more a virus circulates in a population, the more opportunities it has to transform itself and can reduce the effectiveness of our vaccines. Recent studies have shown that the vaccines available in the United States are effective against variants currently circulating, including B.1.617.2. Vaccines interrupt the ability of the virus that causes COVID-19 to move between people and mutate, so it is important for everyone to get vaccinated as soon as they’re eligible. If you have questions or concerns about vaccines, please contact your healthcare professional, state or local health department, or local pharmacist or visit the CDC website. To find a place in your community to get a vaccine, visit Vaccines.gov or your local public health department website.
* To assist with public discussions of variants, the World Health Organizationexternal icon (WHO) recently proposed using labels consisting of the Greek Alphabet (e.g., Alpha, Beta, Gamma, Delta) as a practical way to discuss variants by non-scientific audiences. CDC supports WHO’s effort to a develop simple, non-stigmatizing variant naming system and is now indicating the WHO label for each key variant of interest (VOI) and variant of concern.
** The median time from specimen collection to sequence data reporting is about 3 weeks. As a result, weighted estimates for the most recent few weeks may be unstable or unavailable. CDC’s nowcast is a data projection tool that helps fill this gap by generating timely estimates of variant proportions for variants that are circulating in the United States. View nowcast estimates on CDC’s COVID Data Tracker website on the Variant Proportions page.
SARS-CoV-2 Variants
Multiple variants of the virus that causes COVID-19 are circulating globally and within the United States. To date, six variants have been classified as a variant of concern (VOC). Nowcast estimates* of SARS-CoV-2 cases caused by these VOCs for the two weeks ending June 19 are summarized here. Nationally, B.1.1.7 (Alpha) proportion is predicted to decrease to 52.2%;
B.1.617.2 (Delta) proportion is predicted to increase to 20.6%;
and P.1 (Gamma) proportion is predicted to increase to 16.4%.
Nowcast estimates predict that B.1.1.7 (Alpha) proportions will be more than 50% in HHS regions 3, 4, 5, and 6. B.1.617.2 (Delta) is predicted to increase in all regions and to be more than 45% in regions 7 and 8. P.1 (Gamma) is predicted to be more than 20% in regions 1, 4, 5, and 10; and
B.1.526 (Iota) is predicted to be more than 10% in regions 1, 2, and 3.
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