Influenza — what most of us call "the flu" — is a contagious viral infection of the nose, throat, and lungs. It can make a person feel very sick.
When Should People Get the Flu Vaccine?
Flu season runs from October to May. It's best to get a flu vaccine as early in the season as possible, ideally by the end of October. This gives the body a chance to make antibodies that protect from the flu. But getting a flu vaccine later in the season is better than not getting it at all. Getting a missed flu vaccine late in the season is especially important for people who travel. That's because the flu can be active around the globe from April to September.
Understanding the Flu Vaccine
Get the facts about the flu vaccine and how it can help keep your family healthy each year
Who Should Get the Flu Vaccine?
The Centers for Disease Control and Prevention (CDC) recommends a flu vaccine for everyone 6 months of age and older.
But it's especially important that those in higher-risk groups get vaccinated to avoid health problems from the flu. They include:
all kids 6 months through 4 years old
anyone 65 years and older
all women who are pregnant, are trying to become pregnant, have recently given birth, or are breastfeeding during flu season
anyone whose immune system is weakened from medications or illnesses (like HIV infection)
people who live in long-term care facilities, such as nursing homes
any adult or child with chronic medical conditions, such as asthma or diabetes
kids or teens who take aspirin regularly and are at risk for developing Reye syndrome if they get the flu
caregivers or household members of anyone in a high-risk group (like children younger than 5 years old, especially those younger than 6 months, and those with high-risk conditions)
Native Americans and Alaska Natives
Babies younger than 6 months can't get the vaccine. But if their parents, other caregivers, and older kids in the household get it, that will help protect the baby. This is important because infants are more at risk for serious problems from the flu.
How Is the Flu Vaccine Given?
Kids younger than 9 years old will get two doses of flu vaccine, spaced at least 1 month apart, if they've had fewer than two doses before July 2019. This includes kids who are getting the flu vaccine for the first time.
Those younger than 9 who had at least two doses of flu vaccine (in the same or different seasons) will only need one dose.
Kids older than 9 need only one dose of the vaccine.
Two types of flu vaccine are available for the 2020–2021 flu season. Both protect against the four types of influenza virus that are causing disease this season::
the flu shot, which is injected with a needle
the nasal spray, a mist which gets sprayed into the nostrils
In the past, the nasal spray vaccine wasn't recommended for kids because it didn't seem to work well enough. The newer version appears to work as well as the shot. So either vaccine can be given this year, depending on the child's age and general health.
The nasal spray is only for healthy people ages 2–49. People with weak immune systems or some health conditions (such as asthma) and pregnant women should not get the nasal spray vaccine.
Why Is the Flu Vaccine Recommended?
While the flu vaccine isn't 100% effective, it still greatly reduces a person's chances of catching the flu, which can be very serious. It also can make symptoms less severe if someone does still get the flu after immunization.
Even if you or your kids got the flu vaccine last year, that won't protect you this year, because flu viruses change. That's why the vaccine is updated each year to include the most current types of the virus.
Sometimes the same types are included in the vaccine one year after the next. Even then, it's still important to get the yearly flu vaccine because the body's immunity against the influenza virus declines over time.
What Are the Possible Side Effects of the Flu Vaccine?
Usually given as an injection in the upper arm, the flu shot contains killed flu viruses that will not cause someone to get the flu. But it can cause mild side effects like:
soreness, redness, or swelling at the injection site
In the past, people with an egg allergy had to check with their doctor about whether the flu vaccine was OK for them because it's grown inside eggs. But health experts now say that the amount of egg protein in the vaccine is so tiny that it's safe even for kids with a severe egg allergy. This is especially important during a severe flu season.
Still, a child with an egg allergy (who has had symptoms more severe than hives) should get the flu vaccine in a doctor's office, not at a supermarket, drugstore, or other venue.
If your child is sick and has a fever, or is wheezing, talk to your doctor about whether to reschedule the flu vaccine.
Getting a Flu Vaccine During the COVID-19 Pandemic
The flu season seemed milder during the COVID-19 pandemic, as fewer people got infected or were hospitalized with the flu. Experts are studying why that might be. It could be tied to public health measures that protect against coronavirus, as they also protect against the flu. These include wearing masks in public, social distancing, and lack of travel. Increased flu vaccination rates also might have helped.
COVID-19 may still be getting lots of attention, but many people get very sick or even die from the flu every year. So it's still important to get a flu vaccine each year.
When Should I Call the Doctor?
You aren't sure if the vaccine should be postponed or avoided.
There are problems after the immunization, such as an allergic reaction or high fever, or if you have other concerns.
Reviewed by: Jonathan M. Miller, MD and Elana Pearl Ben-Joseph, MD