Here's what to know about the flu shot, including when to get vaccinated and what signs of the flu to look out for.

By Stacey Leasca
September 26, 2018

The leaves are changing colors, pumpkin spice lattes are everywhere, and the weather is getting just a bit chiller, which can only mean one thing: Flu season is almost here.

With the new fall season comes an increased chance of catching a nasty case of the flu. Thankfully, there are ways to protect yourself and your loved ones from spreading the illness, including getting the flu shot. But, when should you get it, and what does the flu shot actually do? Here’s everything you need to know before heading to the doctor’s office this year.

What is the flu anyway and what are flu symptoms?

Influenza, or “the flu,” is a highly contagious viral respiratory illness. As the Mayo Clinic explains, flu symptoms often mimic the common cold at first and include a “runny nose, sneezing, and sore throat. But colds usually develop slowly, whereas the flu tends to come on suddenly. And although a cold can be a nuisance, you usually feel much worse with the flu.”

Additional flu symptoms include a fever above 100.4 degrees, aches, chills, headaches, and cough.

How long does the flu last?

The US Department of Health and Human Services' National Institute of Aging notes that most people who come down with the flu recover in one to two weeks. The illness is typically more serious for either the very young (under 2) or those over 65, who are more susceptible to secondary illnesses like pneumonia. Other groups more at risk if they get the flu include those with pre-existing medical conditions and pregnant women.

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In terms of how long the illness is contagious for, adults can spread flu viruses one day prior to the appearance of symptoms and up to seven days after symptoms begin.

What does the flu shot protect against?

It’s important to know that the flu shot will not protect you from all the different strains of flu. However, the Centers for Disease Control and Prevention (CDC) aims to update the vaccine each year to try and protect people against the most dangerous strains during flu season. This year, the CDC noted, the seasonal flu vaccine protects against three or four viruses that research suggests will be most common.

Who should get a flu vaccine?

According to the CDC, the flu shot is highly recommended for the most susceptible groups mentioned earlier. While there are different variations of the vaccine, the flu shot most commonly is made using viruses grown in eggs. Don’t worry, if you’re allergic to eggs, the CDC does have an alternative–just make sure to alert your doctor.

Babies under 6 months old and anyone with a life-threatening allergy to the ingredients in the flu shot should not get vaccinated.

When should you get a flu shot?

Literally right now. As the CDC said, “You should get a flu vaccine before flu begins spreading in your community.” It can take up to two weeks for the vaccine to take effect and protect against the flu in the body, which means getting vaccinated in the early fall is best. The CDC recommends that everyone get the flu vaccine, annually, by the end of October at the latest. If you can’t get an appointment, late is better than never.

A flu shot really only lasts for a year because, in addition to the seasonal strains changing, the efficacy of the vaccination declines over time.

What else can you do besides get the flu shot?

Beyond getting the flu shot, the CDC recommends normal prevention procedures like washing your hands frequently, staying clear of sick people, and cleaning your home’s surfaces regularly. If you do get sick, stay home and away from others for the entire duration of your flu, including the 24 hours after your symptoms subside.

For more tips, here's our checklist of the dos and dont's for cold and flu remedies.