Influenza, or the flu, is a contagious respiratory illness caused by the influenza virus that infects the nose, throat and/or lungs. Symptoms include fever, cough, sore throat, runny nose, body aches, headache and fatigue. The virus spreads via droplets when an infected person coughs, sneezes or talks, or, less commonly, by touching a contaminated surface, then touching one's face. According to the U.S. Centers for Disease Control and Prevention, an average of 8% of the U.S. population gets sick with the flu each year, and 12,000-60,000 people die. Getting vaccinated for the flu each year is the best way to prevent infection. 

Influenza Virus Versus SARS-CoV-2

Comparison of influenza virus, which causes the flu, with SARS-CoV-2, which causes COVID-19.
Comparison of influenza virus, which causes the flu, with SARS-CoV-2, which causes COVID-19.
Source: American Society for Microbiology

Influenza on ASM Podcasts

Sept. 26, 2019


Jesse Bloom discusses his research on influenza virus evolution, immunity and cooperation by studying influenza viruses at the human population, cell culture and single cell levels.

Aug. 11, 2019

The purpose of CEIRS, universal influenza vaccines and cellular responses to infection in pediatric populations.

Inadequate Flu Vaccination Rates

Annual vaccination is the best way to protect oneself against the flu. Although the seasonal flu vaccine is widely available, less than 50% of the total U.S. population got vaccinated for the latest season on record. This is a public health concern. Improved funding and education is needed to facilitate widespread coverage.


Influenza vaccination rates for children 6 mos. to 17 years of age by U.S. state for the 2018-2019 flu season.
Influenza vaccination rates for children 6 mos. to 17 years of age by U.S. state for the 2018-2019 flu season.
Source: American Society for Microbiology
Influenza vaccination rates for adults 18 years old and older by U.S. state for the 2018-2019 flu season.
Influenza vaccination rates for adults 18 years old and older by U.S. state for the 2018-2019 flu season.
Source: American Society for Microbiology

Other Flu Resources

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