Note: On June 22, 2016, CDC’s Advisory Committee on Immunization Practices (ACIP) recommended a change to U.S. influenza vaccination policy for 2016-2017. The ACIP recommendation must be reviewed and approved by CDC’s Director, and the final recommendations will be published in a CDC Morbidity and Mortality Weekly Report (MMWR), in late summer or early fall. The content of this website will be reviewed and updated prior to the 2016-2017 influenza season.
While current U.S. flu activity is low, some flu viruses circulate during the summer and influenza activity often begins increasing in October.
CDC recommends a yearly flu vaccine for everyone 6 months and older by the end of October, if possible. Flu vaccination can reduce flu illnesses and prevent flu-related hospitalizations. Flu vaccines have been updated for the 2016-2017 season.
CDC also recommends that patients suspected of having influenza who are at high risk of flu complications or who are very sick with flu-like illness should receive prompt treatment with influenza antiviral drugs without waiting for confirmatory testing.
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There are many different influenza A viruses; some are found in humans and others in animals such as avian flu in birds and poultry.
U.S. H5 Viruses: Highly pathogenic avian influenza (HPAI) H5 infections have been reported in U.S. birds and poultry. No human infections with these viruses have been detected at this time, however similar viruses have infected people in other countries and caused serious illness and death in some cases.
Influenza viruses that normally circulate in pigs are called “variant” viruses when they are found in people. Influenza A H3N2 variant viruses (also known as “H3N2v” viruses) with the matrix (M) gene from the 2009 H1N1 pandemic virus were first detected in people in July 2011.
CDC’s pandemic preparedness efforts include ongoing surveillance of human and animal influenza viruses, risk assessments of influenza viruses with pandemic potential, and the development and improvement of preparedness tools that can aid public health practitioners in the event of an influenza pandemic.
Bat influenza refers to influenza A viruses found in bats. Laboratory research at CDC suggests these viruses would need to undergo significant changes to become capable of infecting and spreading easily among humans. Little yellow shouldered bats are not native to the continental United States, but are common in Central and South America.
Influenza A viruses are found in humans and many different animals, including ducks, chickens, pigs, whales, horses and seals. Additional information on 2009 H1N1 influenza, Flu.gov, and Nonpharmaceutical Interventions (NPIs).
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The latest report on CDC's international flu activities highlights the progress that has been made over the past two fiscal years in establishing, expanding and maintaining influenza surveillance and laboratory capacity in more than 50 countries around the world where CDC has provided support.
- Interim Guidance for Clinicians on Human Infections with Variant Influenza Viruses Monday, August 15, 2016
- Case Count: Detected U.S. Human Infections with H3N2v by State since August 2011 Friday, August 12, 2016
- Reported Infections with Variant Influenza Viruses in the United States since 2005 Friday, August 12, 2016
- 4 Variant Virus Infections Linked to Pig Exposures Friday, August 12, 2016
- New CDC Study: Influenza Vaccination Reduces Risk of Hospitalization By More Than Half Among Seniors Tuesday, August 02, 2016
- Page last reviewed: July 21, 2016
- Page last updated: July 21, 2016
- Content source:
- Centers for Disease Control and Prevention, National Center for Immunization and Respiratory Diseases (NCIRD)
- Page maintained by: Office of the Associate Director for Communication, Digital Media Branch, Division of Public Affairs