About Variants of the Virus that Causes COVID-19/COVID-19変異ウイルスについて​​(English)

Skip directly to site content
Skip directly to search

Self-Checker

Coronavirus Self-Checker

Restart

×

Centers for Disease Control and Prevention. CDC twenty four seven. Saving Lives, Protecting People

×

Submit

HOME
COVID-19

COVID-19

Coronavirus Home

Home

Your Health

Vaccines

Cases & Data

Specific Settings

Healthcare Workers

Health Depts

Science

More

Section Navigation

CDC Home

Important update: Healthcare facilities

CDC has updated select ways to operate healthcare systems effectively in response to COVID-19 vaccination.
Learn more

Find the latest information:

Aquatics FAQs

Recommendations for Fully Vaccinated People

COVID-19 Homepage

UPDATE
Given new evidence on the B.1.617.2 (Delta) variant, CDC has updated the guidance for fully vaccinated people. CDC recommends universal indoor masking for all teachers, staff, students, and visitors to K-12 schools, regardless of vaccination status. Children should return to full-time in-person learning in the fall with layered prevention strategies in place.

UPDATE
The White House announced that vaccines will be required for international travelers coming into the United States, with an effective date of November 8, 2021. For purposes of entry into the United States, vaccines accepted will include FDA approved or authorized and WHO Emergency Use Listing vaccines. More information is available here.

UPDATE
Travel requirements to enter the United States are changing, starting November 8, 2021. More information is available here.

Variants of the VirusVariants of the Virus

Updated Aug. 11, 2021

Print

Minus

Related Pages

What You Need to Know
New variants of SARS-CoV-2, the virus that causes COVID-19, are expected to occur.
CDC is working with state and local public health officials to monitor the spread of all variants.
The Omicron variant continues to spread throughout communities and can infect people who have been vaccinated or have previously had COVID-19.
Staying up to date with your COVID-19 vaccines reduces your risk of severe illness, hospitalization, and death from COVID-19.

Variants in the United States
Numerous variants of the virus that causes COVID-19 are being tracked in the United States and globally during this pandemic. CDC is working with public health officials to monitor the spread of all variants and provide an estimate of how common they are in the nation and at the regional level. This data can change over time as more information is available.
VARIANT OF CONCERNOmicronOriginal Lineage: B.1.1.529
Currently Circulating Lineages: BA.2, BA.4 and BA.5
The Omicron variant, like other variants, is made up of a number of lineages and sublineages.
These lineages are often very similar to each other; however, there may be differences between lineages that affect the behavior of the virus. Visit CDC’s COVID Data Tracker for the most current data on circulating variants.
Omicron spreads more easily than earlier variants, including the Delta variant.
Anyone with Omicron infection, regardless of vaccination status or whether or not they have symptoms, can spread the virus to others. Data suggest that Omicron can cause reinfection, even in people who have recovered from COVID-19.
Symptoms are similar to previous variants
COVID-19 vaccination status, other health conditions, age, and history of prior infection can affect the presence and severity of symptoms.
Omicron causes less severe illness and death in general, according to data
However, a surge in cases may lead to increases in hospitalizations and deaths.
Vaccines help prevent severe illness, hospitalizations, and death
Breakthrough infections in people who are vaccinated are expected. The emergence of the Omicron variant further emphasizes the importance of vaccination and boosters.
Antiviral treatments are effective
Some, but not all, monoclonal antibody treatments remain effective against Omicron. Public health agencies work with healthcare providers to ensure that effective treatments are used appropriately to treat patients.
Variants Are Expected
Viruses constantly change through mutation and sometimes these mutations result in a new variant of the virus. Some variations allow the virus to spread more easily or make it resistant to treatments or vaccines. As the virus spreads, it may change and may become harder to stop.
Regardless of the variant, a surge in cases can impact healthcare resources

Even if a variant causes less severe disease in general, an increase in the total number of cases could cause an increase in hospitalizations, put more strain on healthcare resources, and potentially lead to more deaths.
We Have the Tools to Fight VariantsThe following pages cover more detailed information about specific key prevention actions which can help fight variants.
VaccinesMasksTestingVentilation

Monitoring Variants
CDC uses viral genomic surveillance to quickly identify and track COVID-19 variants, and acts upon these findings to best protect the public’s health. Some variants spread more easily and quickly than others, which may lead to more cases of COVID-19.
Scientists monitor all variants but may classify certain ones as:

Variants Being Monitored – No risk to public health; Circulating at very low levels in the United States
Variants of Interest – Potential impact on spread, severity, testing, treatment, and vaccinations; Evidence it has caused an increase proportion of cases or unique outbreak clusters
Variants of Concern – Evidence of impact on spread, severity, testing, treatment, and vaccination
Variants of High Consequence – Clear evidence of significant impact on spread and severity, and reduction of effectiveness of testing, treatment, and vaccination

In the United States, CDC uses viral genomic surveillance to track COVID-19 variants, to more quickly identify and act upon these findings to best protect the public’s health. CDC established multiple ways to connect and share viral genomic sequence data being produced by CDC, public health laboratories, and commercial diagnostic laboratories within publicly accessible databases.
Learn More About Tracking Variants

Definitions & Classifications

Tracking & Surveillance

US & Global

Variant Data

Last Updated Aug. 11, 2021 Source: National Center for Immunization and Respiratory Diseases (NCIRD), Division of Viral Diseases

Facebook
Twitter
LinkedIn
Syndicate

homeYour HealthAbout COVID-19plus iconVariantsplus iconUnderstanding VariantsTransmissionplus iconHow COVID-19 SpreadsReinfectionAntibodiesAnimals & COVID-19Basics of COVID-19SymptomsTestingplus iconSelf-Testingplus iconSelf-Testing VideosViral Testing ToolUnderstanding Your Riskplus iconRisk of Getting Very SickExposure RisksImmunocompromisedMedical ConditionsPregnant PeopleAsthmaCOVID-19 by CountyProtect Yourself & Othersplus iconVaccinesMasksplus iconTypes of Masks and RespiratorsUse and Care of MasksFind Free Masks (N95 Respirators)How to Use Your N95 RespiratorFree N95 Respirator ManufacturersVentilationplus iconInteractive Home Ventilation ToolIf You Were ExposedIf You Are Sickplus iconWhat to Do If You Are SickIsolationCaring for SomeoneBreastfeeding & Caring for NewbornsTreatments & MedicationsLong COVIDplus iconCaring for People with Long COVIDPatient Appointment TipsTravelplus iconDomestic Travel During COVID-19International Travel to and from the United Statesplus iconRequirement for Proof of COVID-19 Vaccination for Air PassengersMask RecommendationCruise Ship TravelTravel FAQs

email_03Get Email Updates To receive email updates about COVID-19, enter your email address: Email Address What’s this? Submit

About CDC
Contact Us
800-232-4636

Facebook
Twitter
Instagram
LinkedIn
Youtube
Pinterest
Snapchat

CONTACT CDC

Contact Us

Call 800-232-4636

Email Us

ABOUT CDC

About CDC
Jobs
Funding

POLICIES

Accessibility
External Links
Privacy
Policies
No Fear Act
FOIA
OIG
Nondiscrimination
Vulnerability Disclosure Policy

CONNECT WITH US

Facebook
Twitter
Instagram
LinkedIn

Youtube
Pinterest
Snapchat

LANGUAGES

Español
繁體中文
Tiếng Việt
한국어
Tagalog
Русский
العربية
Kreyòl Ayisyen
Français
Polski
Português
Italiano
Deutsch
日本語
فارسی
English

Español
繁體中文
Tiếng Việt
한국어
Tagalog
Русский
العربية
Kreyòl Ayisyen
Français
Polski
Português
Italiano
Deutsch
日本語
فارسی
English

Accessibility
External Links
Privacy
Policies

No Fear Act
FOIA
OIG
USA.gov

Nondiscrimination
Vulnerability Disclosure Policy
Department of Health & Human Services
COVID-19 Web Archive

COVID-19 Web Archive

U.S. Department of Health & Human Services

USA.gov

SAS

stats

Exit Notification / Disclaimer Policy

Close

Links with this icon indicate that you are leaving the CDC website.

The Centers for Disease Control and Prevention (CDC) cannot attest to the accuracy of a non-federal website.
Linking to a non-federal website does not constitute an endorsement by CDC or any of its employees of the sponsors or the information and products presented on the website.
You will be subject to the destination website’s privacy policy when you follow the link.
CDC is not responsible for Section 508 compliance (accessibility) on other federal or private website.

For more information on CDC’s web notification policies, see Website Disclaimers.

Cancel
Continue

CDC.gov Privacy Settings

We take your privacy seriously. You can review and change the way we collect information below.

Performance Cookies Checkbox

Performance Cookies

These cookies allow us to count visits and traffic sources so we can measure and improve the performance of our site. They help us to know which pages are the most and least popular and see how visitors move around the site. All information these cookies collect is aggregated and therefore anonymous. If you do not allow these cookies we will not know when you have visited our site, and will not be able to monitor its performance.

Functional Cookies Checkbox

Functional Cookies

Cookies used to make website functionality more relevant to you. These cookies perform functions like remembering presentation options or choices and, in some cases, delivery of web content that based on self-identified area of interests.

Campaign Cookies Checkbox

Campaign Cookies

Cookies used to track the effectiveness of CDC public health campaigns through clickthrough data.

Social Media Cookies Checkbox

Social Media Cookies

Cookies used to enable you to share pages and content that you find interesting on CDC.gov through third party social networking and other websites. These cookies may also be used for advertising purposes by these third parties.

Remove all

Confirm Choices

Confirmed!
Thank you for taking the time to confirm your preferences. If you need to go back and make any changes, you can always do so by going to our Privacy Policy page.
Close