Information for Flu Care Providers - ILI Surveillance Reports
Influenza (flu) severity varies from year to year, but flu always brings serious consequences

The prevention of influenza is important every year. The flu vaccine lowers the risk of influenza-related illness, hospitalization, and death.![]()
The COVID-19 pandemic means preventing influenza during 2020–21 is more important than ever. Influenza and COVID-19 share many symptoms. Preventing influenza means fewer people will need to seek medical care and testing for possible COVID-19 or influenza. And increasing flu vaccination uptake saves healthcare resources for COVID-19 and other conditions. Begin recommending flu vaccine now, and vaccinate throughout the flu season, providing extra outreach to those at highest risk of severe COVID-19 or severe influenza.
Flu Vaccine prevents the flu and severe outcomes of the flu
Flu Vaccine is not always a perfect match for the circulating flu virus types. But there are flu outbreaks every year that cause severe illness. Flu vaccine prevents:
- Missed work days
- Missed school days
- Additional doctor appointments, medicines, and treatments
- Flu symptoms that can mimic COVID-19, saving healthcare resources needed for COVID-19 care.
What is Influenza (also called flu)?
The flu is a contagious respiratory illness caused by influenza viruses. It can cause mild to severe illness, and at times can lead to death. The best way to prevent the flu is by getting a flu vaccine each year.
Symptoms of the Flu
People who have the flu often feel some or all of these symptoms:
- fever* or feeling feverish/chills
- cough
- sore throat
- runny or stuffy nose
- muscle or body aches
- headaches
- fatigue (very tired)
- Some people may have vomiting and diarrhea, though this is more common in children than adults
*It’s important to note that not everyone with flu will have a fever.
How the Flu Spreads
Most experts believe that flu viruses spread mainly by droplets made when people with flu cough, sneeze, or talk. These droplets can land in the mouths or noses of people who are nearby. Less often, a person might also get flu by touching a surface or object that has flu virus on it and then touching their own mouth, eyes, or nose.
Period of Contagiousness
You may be able to pass on the flu to someone else before you know you are sick, as well as while you are sick. Most healthy adults may be able to infect others beginning 1 day before symptoms develop and up to 5-7 days after becoming sick. Some people, especially children and people with weakened immune systems, might be able to infect others for an even longer time.
How Serious is the Flu?
Flu is unpredictable and how severe it is can vary widely from one season to the next depending on many things, including:
- what flu viruses are spreading
- how much flu vaccine is available
- when vaccine is available
- how many people get vaccinated
- how well the flu vaccine is matched to flu viruses that are causing illness
Flu seasons are unpredictable and can be severe. In the United States, thousands of healthy adults and children have to visit the doctor or are hospitalized from flu complications each year and some die. Studies going back to 1976 have found that flu-related deaths ranged from a low of 4,700 to a high of 56,600 (average 25,500).
During a regular flu season, about 90 percent of deaths occur in people 65 years and older. During 2009-2010, a new and very different flu virus (called 2009 H1N1) spread worldwide causing the first flu pandemic in more than 40 years. It is estimated that the 2009 H1N1 pandemic resulted in more than 12,000 flu-related deaths in the U.S. In contrast to seasonal flu, nearly 90 percent of the deaths occurred among people younger than 65 years of age.
What You Need to Know About the Flu Vaccine
A seasonal vaccine is distributed routinely every year. While there are many different flu viruses, this year the majority of flu vaccines protects against the four viruses that research suggests will be most common. The 2021-22 influenza vaccine are made to protect against the following four viruses:
- an A/Victoria/2570/2019 (H1N1) pdm09-like virus;
- an A/Cambodia/e0826360/2020 (H3N2)-like virus;
- a B/Washington/02/2019- like virus (B/Victoria lineage)
- a B/Phuket/3073/2013-like virus (B/Yamagata lineage)
For more information on the 2021-2022 flu vaccine recommendations please go to https://www.cdc.gov/flu/season/faq-flu-season-2021-2022.htm
Resources
A Strong Defense Against Flu: Get Vaccinated!
Una fuerte defensa contra la influenza (gripe): ¡Vacúnese!
What You Should Know About Influenza (Flu) Antiviral Drugs
Lo que debe saber sobre los medicamentos antivirales contra la influenza (gripe)
Pregnant? You Need a Flu Shot!
¿Está embarazada? ¡Usted necesita la vacuna contra la influenza!
Influenza Is a Serious Disease... Make sure your child is protected!
La gripe (influenza) es una enfermedad grave… ¡Proteja a su hijo!
Keep your kids safe — get them vaccinated every fall or winter!
Mantenga a salvo a sus hijos: ¡Vacúnelos cada otoño o invierno!
Adults 65 and Older Need a Flu Shot
Posters:
Fight Flu - English
Fight Flu - Spanish
For Children:
Ready Wrigley Prepares for Flu Season - Activity Book