It’s safe to get a flu shot at any time during pregnancy. Getting the flu vaccine while pregnant protects both you and your baby. For best protection, get the flu shot annually by the end of October. Don't worry – you can’t catch the flu from the flu vaccine.
Is it safe to get a flu shot during pregnancy?
Yes. According to the Centers for Disease Control and Prevention (CDC) and other government health agencies, the flu shot has been proven safe and effective for pregnant women and their babies at all stages of pregnancy, including the first trimester.
Not only is getting a flu shot safe during pregnancy; it's strongly recommended. You can take preventive measures – such as washing your hands and staying away from people who are sick – but when it comes to the flu during pregnancy, the CDC says vaccination is the best way to protect yourself. Experts at the American College of Obstetricians and Gynecologists, the American College of Nurse-Midwives, the American Academy of Pediatrics, and many other organizations agree.
There's also an important benefit to your baby: Antibodies that you develop during pregnancy in response to the flu shot are passed to your baby and provide protection from the flu for several months after birth. That protection can be vital because babies younger than 6 months are especially vulnerable to complications but are too young to be vaccinated against the illness.
Note: The nasal spray flu vaccine is not recommended for pregnant women because it contains a tiny amount of weakened live virus.
Is there any danger of catching the flu from the flu vaccine?
No – there’s no chance. Flu shots do not contain the live virus, which is the only thing that can cause the flu.
Flu shots contain fragments of killed influenza virus, which stimulate your body to produce antibodies that protect you from the live virus. But the influenza virus in the flu shot is inactive, so it can't infect you.
How effective is the flu shot?
Flu shots significantly lower your chances of getting severe flu, and are very effective at protecting your baby.
A recent study showed that pregnant women's risk of being hospitalized for the flu dropped an average of 40 percent if they had received flu shots. Getting a flu vaccination while pregnant has also been shown to halve the risk of getting the upper respiratory infections the flu can cause.
Your baby benefits too. Babies born to women who have been vaccinated against the flu have a 70 percent lower risk of getting the illness before they are 6 months old compared to infants born to women who didn't get flu shots, research shows.
There are many different flu viruses, and each year the flu vaccine is made to protect against three or four strains predicted to be most common that season. This means it's still possible to get sick with flu even if you've been vaccinated. But studies show the flu shot can reduce the severity of your illness.
When should I get the flu shot?
You need a flu shot every year even if you've had one in previous years because different strains of flu surface each year.
No matter which trimester you're in, get the flu vaccine when it becomes available – preferably by the end of October, so you're protected before flu season begins. (It takes about two weeks for your body to make the antibodies.) But if you miss getting a shot in the fall, it's still worth getting vaccinated afterward because the flu season can last into May.
Where can I get the flu shot?
You can most likely get the shot from your healthcare provider at a prenatal visit, but many pharmacies also offer vaccinations. If you can't find one, call your local health department to find out where the flu shot is available in your community, or try HealthMap's flu vaccine finder.
What are the possible side effects of the flu vaccine?
Side effects are usually mild. Common ones can include:
- Soreness, redness, or swelling at the injection site
- Muscle aches
If you do have side effects, they usually begin soon after you get the shot, and may last a day or two.
As with any vaccine, severe allergic reactions are very rare but possible. Signs of serious allergic reaction can include:
- Breathing problems
- Hoarseness or wheezing
- Fast heartbeat
Severe reactions usually develop within a few minutes to a few hours after you get the shot. Call 911 if you start having any symptoms of a serious reaction.
Does the flu vaccine contain thimerosal?
Some flu vaccines that are stored in multidose vials prior to being drawn for a single-dose flu shot contain thimerosal (a preservative that contains a type of mercury) to safeguard against contamination of the vial.
Manufacturers stopped using thimerosal in children's vaccines in 2001, except for in multidose vials of flu vaccine. Most single-dose vials and prefilled syringes of flu vaccine and the nasal spray flu vaccine do not contain preservatives because they are intended to be used once.
The CDC considers thimerosal safe for pregnant women and their developing babies, but if you'd like to get a thimerosal-free vaccine, just ask. They're usually available.
Who should not get the flu shot?
Don't get a flu vaccine if:
- You've had a severe allergic reaction to a flu shot.
- You're allergic to eggs. (However, if you only get hives after exposure, you can still get the flu shot.)
If you have a serious allergic reaction to eggs, you can get the vaccine under medical supervision. (Chicken eggs are used as a culture for growing the flu virus that's used in most vaccines.)
Before getting a flu shot, be sure to let your healthcare provider know if you have any other severe allergies, or if you've had the rare immune disorder Guillain-Barré syndrome.
Where can I get more information?
For the most up-to-date information on the current flu season, check the CDC's flu site, or call the CDC at (800) CDC-INFO or (800) 232-4636.
Editor's note: Most of this article is adapted from information published by the U.S. Centers for Disease Control and Prevention (CDC).