What to know about the flu vaccine and pregnancy
If you’re pregnant, your doctor is going to strongly recommend that you get the flu vaccine. This is because based on the available science, the known risks of getting the flu outweigh the potential risks of getting the flu vaccine. For most healthy adults, the flu typically isn’t a big deal. But if you are pregnant, you are at much higher risk for complications from the flu, which can be dangerous and even fatal.
The 2020/2021 flu season
Getting the flu shot is particularly relevant to the upcoming 2020/2021 flu season because complications from the flu will also increase the likelihood of you having to go to the hospital, which will put more stress on the healthcare system and put you at higher risk for contracting COVID-19. Because of this, experts are doubling down on their recommendation that we all — but especially those of us who are pregnant — get a flu shot.
How does the flu affect your body during pregnancy?
When you’re pregnant, your body’s chemicals actually change and as a result, you are at risk of getting more sick from the flu than other healthy adults. Why? A 2014 study from Stanford University revealed that people who are pregnant have an unusually strong immune response to the influenza virus. This causes your body to release large amounts of inflammatory cells, which lead to more severe symptoms — like a high fever, runny nose, sore throat, muscle pains, headache, coughing, and fatigue — and more frequent complications, such as pneumonia and a sinus infection. The authors of the same 2014 Stanford study also suspect that physiological changes — like immunological changes, increased cardiac output, oxygen consumption, and lung volume — may also be to blame for the increase in flu complications during pregnancy.
How does the flu vaccine affect your body during pregnancy?
The side effects of the flu vaccine for people who are pregnant are similar to those experienced by other healthy adults. They include soreness, redness, or swelling at the injection site and headache, fever, muscle aches, fainting, nausea, and fatigue. These side effects are typically mild and last for 1 to 2 days. It’s very rare but flu shots can cause a severe allergic reaction. There is one study that showed that one type of influenza virus vaccine elicited a measurable inflammatory response in people who are pregnant; that said, the researchers on the study noted that that inflammatory response created by the vaccine is milder and less concerning than that created by the flu itself.
MYTH: The flu vaccine can cause a miscarriage.
- Some people are concerned that the inflammation caused by the flu shot may cause a miscarriage or pregnancy complications, especially during the first trimester. This is because one study on 585 participants published in the journal Vaccine found a correlation between first trimester miscarriage and the flu vaccine.
- This study made headlines, but it does not establish a causal relationship between repeated influenza vaccination and miscarriage. After the study was published, the CDC and ACOG released statements saying that they recommend the flu shot for expecting mothers, even during the first trimester.
What type of flu vaccine is best for people who are pregnant?
- If you do decide to get the flu shot, you have options because there are a few different versions to choose from.
- The CDC does not recommend the LAIV or nasal spray vaccine, which use live attenuated virus, during pregnancy.
- The other version of the flu shot is an injection that contains flu virus that has been killed.
- Multi-dose vaccines: This version of the flu shot contains about 25 micrograms of thimerosal, a type of mercury. According to the World Health Organization, this is a very small amount of mercury compared to other sources and there is no evidence that the thimerosal in a flu vaccine can cause health issues.
- Single dose vaccines: If you want to avoid mercury altogether, you can request a single-dose vaccine, which is mercury-free.
What can you do to prevent the flu?
- The best way to prevent the flu is to get a flu shot, which can reduce your risk by an average of 40 to 60%, depending on the year. If you get the vaccine, it is still possible to get the flu because there are multiple strains of the flu every year and antibodies take about two weeks to develop in the body.
- Whether or not you decide to get the flu vaccine, there are steps you can take to prevent the flu: wash your hands, avoid touching your face, and stay away from friends, family members, or co-workers who are sick.
This article was produced in partnership with Pregnancy Podcast, an evidence-based podcast dedicated to providing people who are pregnant and their supporters with thoroughly researched, high quality information about fertility, pregnancy, birth and beyond.