Is the influenza (flu) vaccine safe during pregnancy?

From the Guidelines

The flu vaccine is safe during pregnancy and is strongly recommended for all pregnant women. The vaccine is given as a single dose, typically as an injection in the arm, and provides protection against the most common strains of influenza virus expected in the upcoming season. Pregnant women can receive the flu shot at any time during pregnancy, as stated in the most recent guidelines from the Advisory Committee on Immunization Practices 1. However, they should only get the inactivated flu vaccine (the shot) and not the live attenuated vaccine (nasal spray).

The optimal timing is before or during flu season, which typically runs from October through May in the Northern Hemisphere. No additional preparation is needed before getting the vaccine. The flu vaccine is particularly important during pregnancy because pregnant women are at higher risk of severe complications from influenza due to changes in their immune system, heart, and lungs, as highlighted in a recent report 1. The vaccine not only protects the mother but also provides antibodies that cross the placenta and protect the newborn for several months after birth, when babies are too young to receive their own flu vaccine.

Side effects are generally mild and may include soreness at the injection site, low-grade fever, or mild body aches, which typically resolve within 1-2 days. According to the latest recommendations, influenza vaccination during pregnancy is associated with reduced risk for respiratory illness and influenza among pregnant and postpartum persons as well as infants during the first months of life 1. While some studies have raised concerns about the potential risks of influenza vaccination during pregnancy, the majority of the evidence suggests that the benefits of vaccination outweigh the risks, and the vaccine is safe for use in pregnant women 1.

Key points to consider include:

• The flu vaccine can be administered at any time during pregnancy, including the first trimester 1.
• Pregnant women should receive the inactivated flu vaccine (the shot), not the live attenuated vaccine (nasal spray) 1.
• The vaccine provides protection not only for the mother but also for the newborn, who will receive antibodies through the placenta 1.
• Side effects are generally mild and temporary, and the benefits of vaccination outweigh the risks 1.

From the Research

Safety of Flu Vaccine During Pregnancy

• The flu vaccine is considered safe for use during pregnancy, with numerous studies supporting its efficacy and safety 2, 3, 4, 5, 6.
• The Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices and the American College of Obstetricians and Gynecologists recommend that all pregnant women receive an inactivated influenza vaccine as soon as it is available 2.
• The vaccine can be given safely during any trimester, and it is recommended that obstetrician-gynecologists and other obstetric care providers recommend and advocate for the influenza vaccine 2.
• Studies have shown that influenza vaccination during pregnancy can offer direct protection to pregnant women and passive immunity to infants up to 6 months of age via maternal antibodies 4.
• The safety of oseltamivir, an antiviral medication used to treat influenza, has also been assessed during pregnancy, with studies suggesting that it is unlikely to cause adverse pregnancy or fetal outcomes 6.

Benefits of Flu Vaccine During Pregnancy

• Influenza vaccination during pregnancy can prevent serious illness, including a higher chance of progressing to pneumonia, and reduce the risk of intensive care unit admission and adverse perinatal and neonatal outcomes 2, 3.
• The vaccine can also reduce the risk of birth defects and other adverse pregnancy outcomes associated with influenza infection during pregnancy 6.
• Influenza vaccination during pregnancy has been shown to be effective in preventing disease among exposed individuals and shortening the duration of illness and lessening the likelihood of complications among those infected 3.

Recommendations for Flu Vaccine Use During Pregnancy

• The American College of Obstetricians and Gynecologists recommends that all pregnant women receive an inactivated influenza vaccine as soon as it is available, regardless of trimester 2.
• Obstetrician-gynecologists and other obstetric care providers should recommend and advocate for the influenza vaccine, and consider stocking and administering the vaccine in their offices 2.
• Pregnant women who cannot receive the vaccine in their healthcare provider's office should be referred to another healthcare provider, pharmacy, or community vaccination center 2.