Influenza A: What You Need to Know

02.15.2025 | 2 min read

Amy Barczy is a former brand journalist who authored...

Mother on the phone holding her hand to her sick son's forehead worried about Influenza A

Many of us may believe that spring marks the end of flu season, but that’s not quite the case. While flu season typically peaks between December and February, according to the Centers for Disease Control (CDC), there are cases that occur throughout the year.

In recent weeks, health officials in Michigan reported influenza is "very high." Across the country and in Michigan, Influenza A is the main type in circulation. The virus can pose a risk – especially to certain groups and those with compromised immune systems. To avoid the spread of flu and stay healthy, it’s important to remember to frequently wash your hands, cover your mouth when coughing, stay home if you’re sick and keep up to date with the flu shot.

What is Influenza A?

There are two main types of the influenza virus that cause severe illness in humans: Influenza A and Influenza B. Influenza A has several types, including H1N1 and H3N2. Influenza A can cause severe flu infections in children and adults. It’s a highly contagious respiratory illness that spreads through the tiny drops of bodily fluid shared by talking, sneezing or coughing.

What are symptoms the flu?

Symptoms come on suddenly. Influenza A often has the same symptoms of Influenza B:

Congestion or runny nose
Cough
Fatigue
Fever or chills – though not everyone will experience fever
Headache
Muscle or body aches
Some individuals may experience vomiting and diarrhea, though this is more common in children
Sore throat

Symptoms should resolve in under two weeks, but complications can develop. They can be moderate, like an ear infection, or serious, like pneumonia. Some individuals are at a higher risk of complications from the flu:

Children, especially young children and those under the age of 2 years
Pregnant women
Adults age 65 years and older
Individuals with underlying medical conditions

How to prevent the flu

Flu vaccines are the best way to prevent Influenza A and B. It’s not too late to receive a flu shot, especially if flu is still prevalent. More than 66% of Michigan residents have received a flu shot for this season, according to the Michigan Department of Health and Human Services.

Everyone ages six months old and up should receive a flu shot each flu season. Flu shots can be obtained at the same time as other vaccines, including the COVID-19 vaccines. Pregnant women should receive a flu shot during each pregnancy. Find a flu shot near you.

Related:

Photo credit: Getty Images