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    • CDC Confirms First Human Infection with Flu Virus from Pigs During 2022 Friday, August 5, 2022
    • CDC Director Adopts Preference for Specific Flu Vaccines for Seniors Thursday, June 23, 2022
    • ACIP Flu Meeting Update: Flu Vaccines Worked Better than Reported & ACIP Recommends Specific Vaccines For Seniors Thursday, June 23, 2022
    • UPDATE: U.S. Case of Human Avian Influenza A(H5N1) Virus Reported Thursday, May 5, 2022
    • CDC-Coauthored Study Shows Room for Improvement in Antiviral Use and Vaccination Rates for Flu in U.S. Hospitalized Children Wednesday, May 4, 2022

    Page last reviewed: January 30, 2020
    Content source: Centers for Disease Control and Prevention, National Center for Immunization and Respiratory Diseases (NCIRD)
    • About Fluplus icon
      • What You Need to Know
      • When Is Flu Season
      • How Flu Spreads
      • Understanding Influenza Virusesplus icon
        • Types of Influenza Viruses
        • How Flu Viruses Can Change
        • Human Serology & Flu
        • Antigenic Characterization
        • Genetic Characterization
        • Reconstruction of the 1918 Influenza Pandemic Virus
        • Advanced Molecular Detection
      • Burden of Fluplus icon
        • 2021-2022 Preliminary In-Season Burden Estimate
        • How CDC Estimates Burden
        • Why CDC Estimates the Burden of Flu
        • Past Seasons
        • Frequently Asked Questions
      • How CDC Classifies Flu Severity
      • Glossary of Influenza (Flu) Terms
      • Questions & Answers
    • Who is at Higher Risk of Flu Complicationsplus icon
      • Adults 65 & Over
      • Adults with Chronic Conditionsplus icon
        • Asthma
        • Heart Disease & Stroke
        • Diabetes
        • Chronic Kidney Disease
      • Pregnancyplus icon
        • Flu Vaccine Safety and Pregnancy
      • People With Disabilities
      • HIV/AIDS
      • Cancer
      • Racial and Ethnic Minority Groups
      • What Parents Need to Knowplus icon
        • Caregivers of Infants
        • Young Children
        • Children With Neurologic Conditions
        • Children and Antiviral Drugs
        • Mixing Oseltamivir Capsules for Children
    • This Flu Seasonplus icon
      • 2021-2022 Flu Season FAQ
      • Past Flu Seasonsplus icon
        • 2020-2021
        • 2019-2020
        • 2018-2019
        • 2017-2018
        • 2016-2017
        • 2015-2016
        • 2014-2015
        • 2013-2014
        • 2012-2013
        • 2011-2012
        • 2010-2011
        • 2009-2010
        • 2007-2008
        • 2006-2007
    • Prevent Fluplus icon
      • How to Prevent Flu
      • Key Facts About Flu Vaccines
      • Who Needs a Flu Vaccineplus icon
        • Who Should & Who Should NOT Get Vaccinated
      • Vaccine Benefitsplus icon
        • Publications on Vaccine Benefits
      • Different Flu Vaccinesplus icon
        • Flu Shot
        • Live Attenuated Influenza Vaccine (LAIV)/Nasal Spray Vaccine
        • Quadrivalent Influenza Vaccine
        • High-Dose Flu Vaccine
        • Adjuvanted Flu Vaccine
        • Cell-Based Flu Vaccine
        • Recombinant Flu Vaccine
        • Flu Vaccination by Jet Injector
      • How Flu Vaccines are Madeplus icon
        • Advancements in Influenza Vaccines
        • Selecting Viruses for the Seasonal Influenza Vaccine
      • Flu Vaccine Safetyplus icon
        • Vaccine Safety Questions & Answers
        • Febrile Seizures Following Vaccination
        • Flu Vaccine and People with Egg Allergies
        • Guillain-Barré Syndrome (GBS)
        • Thimerosal
      • Misconceptions about Flu Vaccines
      • Healthy Habits to Help Prevent Flu
      • Vaccine Supply & Distributionplus icon
        • Vaccine Supply for 2021-2022 Season
        • Frequently Asked Questions on Vaccine Supply
        • Historical Reference of Vaccine Doses Distributed
    • Flu Vaccines Workplus icon
      • How Well Flu Vaccines Work
      • CDC’s Vaccine Effectiveness Networksplus icon
        • US Flu VE Network
        • Hospitalized Adult Influenza Vaccine Effectiveness Network (HAIVEN)
        • Influenza and Other Viruses in the Acutely Ill (IVY)
        • Respiratory Virus Transmission Network (RVTN)
        • Randomized Assessment of Influenza Vaccine Efficacy Network (RAIVEN)
      • How Vaccine Effectiveness and Efficacy are Measured
      • Why CDC Estimates Vaccine Effectiveness
      • Vaccine Effectiveness Studiesplus icon
        • 2021-2022 Vaccine Effectiveness
        • Past Seasons Vaccine Effectivenessplus icon
          • VE Tables for 2011-12
          • VE Tables for 2012-13
          • VE Tables for 2013-14
          • VE Tables for 2014-15
          • VE Tables for 2015-16
          • VE Tables for 2016-17
          • VE Tables for 2017-18
          • VE Tables for 2018-19
          • VE Tables for 2019-20
      • Flu Burden Averted from Vaccinationplus icon
        • How CDC Estimates Burden Averted
        • Why CDC Estimates Burden Averted
        • Past Seasons Burden Averted Estimates
    • Symptoms & Diagnosisplus icon
      • Flu Symptoms & Complicationsplus icon
        • What People with a Staph Infection Should Know about Flu
      • The Difference Between Cold and Flu
      • The Difference between Flu and COVID-19
      • Diagnosis
    • Treatmentplus icon
      • What You Need to Know
      • What are Flu Antiviral Drugsplus icon
        • Antiviral Drug Resistance
        • Baloxavir Marboxil
      • What to do if You Get Sick
      • Caring for Someone Sick
    • Schools, Businesses & Travelersplus icon
      • Schools & Childcare Providersplus icon
        • Guidance for School Administrators
        • Cleaning & Disinfecting Schools
        • School-Located Vaccination
      • Business & Employersplus icon
        • Prevent Flu in the Workplace
        • Promoting Vaccination in the Workplace
        • Resources for Hosting a Vaccination Clinic
        • Stay Home When Sick
      • Travelers
    • Flu Activity & Surveillanceplus icon
      • CDC's WHO Collaborating Center
      • Overview of Influenza Surveillance in the United States
      • Influenza Hospitalization Surveillance Network (FluSurv-NET)
      • Current United States Flu Activity Map
      • Weekly U.S. Influenza Surveillance Report (FluView)
      • FluView Interactive
      • Past Weekly Surveillance Reports
      • FluSight: Flu Forecastingplus icon
        • Current Week's Flu Forecast
        • About CDC’s Flu Forecasting Efforts
        • Previous Forecasts for the 2021-2022 Season
    • Health Professionalsplus icon
      • 2021-22 ACIP Summaryplus icon
        • Background and Epidemiology
        • Links to Current & Past Guidance
        • 21-22 ACIP Table
      • Vaccinationplus icon
        • Flu Vaccines and Pregnancy
        • Vaccine Dosage & Administration
        • For Clinicians: Vaccination Summary
        • For Clinicians: Vaccine Safety
        • Reallocating Influenza Vaccine
        • Vaccination Settings
        • Make a Strong Flu Vaccine Recommendation
        • Tools to Prepare Your Practice for Flu Season
      • Information for Clinicians on Influenza Virus Testingplus icon
        • Overview of Influenza Testing Methods
        • Multiplex Assays Authorized for Simultaneous Detection of Influenza Viruses and SARS-CoV-2
        • Information on Collection of Respiratory Specimens for Influenza Virus Testing
        • Clinical Signs & Symptoms of Influenza
        • Symptoms & Laboratory Diagnosis
        • Information for Clinicians on Rapid Diagnostic Testing for Influenza
        • Rapid Influenza Diagnostic Tests (RIDTs)
        • Guidance: Use of Rapid Diagnostic Test
        • Information on Rapid Molecular Assays, RT-PCR, and other Molecular Assays for Diagnosis of Influenza Virus Infection
        • Nucleic Acid Detection Based Tests
        • Medical Office Telephone Evaluation
        • Parotitis and Influenza
        • FAQ Parotitis and Influenza
        • Algorithm: Interpreting Influenza Testing Results When Influenza is Circulating
        • Algorithm: Interpreting Influenza Testing Results When Influenza is NOT Circulating
        • Guide: Considering Influenza Testing
        • Guide: Influenza Diagnostic Testing in Closed Setting Outbreaks
      • Information for Laboratoriesplus icon
        • Rapid Diagnostic Testing
        • Guidance: Standard-Based Electronic Laboratory Reporting
        • Influenza Virus Testing Methods
      • Antiviral Drugsplus icon
        • For Clinicians: Antiviral Medication
        • Types of Antiviral Drugs
        • Antiviral Guidance Reference Material
        • Guidance: Antiviral and Obstetric Health Care
        • Antiviral Drug Supply
      • Infection Controlplus icon
        • Guidelines for Healthcare Settings
        • Respiratory Infection Control Measures
        • Guidance: Outbreak Management in Long-Term Care Facilities
        • Guidance: Use of Mask to Control Influenza Transmission
        • Guidance: Prevention & Control in Peri- and Postpartum Settings
      • Toolkit for Long-Term Care Employers
      • Trainings
      • Health Professional References & Resources
    • Flu News & Spotlightsplus icon
      • 2021-2022
      • 2020-2021
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      • 2017-2018
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      • 2015-2016
      • 2014-2015
      • 2013-2014
      • 2012-2013
      • 2011-2012
      • 2010-2011
      • 2009-2010
    • What's New
    What CDC Does
    • FluVaxView
    • Communications Resource Center
    • International Work
    • Outbreak Investigations
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