Flu makes a lot of people sick every year. Some of us, such as seniors, pregnant women, and children, are at increased risk of developing severe complications, including death. Not surprisingly, on the one hand, pregnant women would like to get protected by the vaccine, but on the other hand, they are worried about any potential effect on their future child. In this article, I will talk about indications, contraindications, and safety of flu vaccine for you when you are pregnant.
The CDC’s Advisory Committee on Immunization Practices and ACOG (The American College of Obstetricians and Gynecologists) recommend that: “all adults receive an annual influenza vaccine and that women who are or will be pregnant during influenza season receive an inactivated influenza vaccine as soon as it is available” (ACOG source article).
Why do they recommend you to get a flu vaccine when you are pregnant?
Many people who contract flu have a benign course and recover completely without any sequelae. However, flu in young children, pregnant women, and seniors may lead to severe conditions with complications requiring hospitalization. Despite questions about the flu vaccine effectiveness, epidemiologists estimated that during influenza season 2017-2018, vaccination programs had prevented approximately 7.1 million illnesses, over 100 000 hospital admissions, and 8000 deaths (CDC source).
Patients who acquire flu while pregnant or soon after delivery are at much higher risk of requiring hospitalization, admission to ICU, or even death. Children can not be vaccinated against flu until they are six months old; therefore, the only way for them to acquire immunity is to get antibodies from the mother through the placenta (CDC immunization calendar). The passage of antibodies takes place during the third trimester. Hence mother must get immunized early enough for that process to take place.
Specific recommendations for pregnant women regarding the flu vaccine.
- All pregnant women who do not have contraindications should receive a flu vaccine.
- Pregnant women should not receive a live-virus flu vaccine. They should be given an inactivated virus vaccine.
- Women can receive the vaccine during any trimester (time) while being pregnant. In order to benefit the baby and allow for passive transfer of the antibodies to the baby, the vaccine should be given at least four weeks before the calculated due date.
- Women with a history of egg allergy, causing only hives, can receive any vaccine otherwise recommended for their age and health condition.
- If a woman has a history of allergy to eggs, causing more severe symptoms, she should be given the vaccine in a special setting prepared for treating allergic reactions.
- Having an allergic reaction to the previous administration of the flu vaccine is a contraindication to this vaccine in the future.
Are there any safety concerns regarding the flu vaccine for pregnant patients?
Based on available studies, CDC and ACOG opined that flu vaccinations are safe and desirable for pregnant patients. To increase your confidence, I will review a few studies that provided information on safety and outcomes for women and children after the flu vaccine had been given during pregnancy.
To date, only one case-control retrospective study raised the possibility of an association between the flu vaccine and subsequent spontaneous abortion in 28 days following the administration of the vaccine. Donahue and coauthors published the study in 2017and included data from only 485 patients (when you study vaccines effects, 485 cases is considered to be a very small number and potentially unreliable). Their research found an association between receipt of an influenza vaccine containing A/H1N1 virus in the first trimester and spontaneous abortion within 28 days only for the women who also had received similar vaccines during the previous season (Source article).
Pedro Moro, with coauthors, published data on the safety of flu vaccinations among pregnant patients covering 19 years between 1990-2009. He searched through the Vaccine Adverse Event Reporting System (VAERS) to determine the safety of the flu vaccine. The most commonly reported pregnancy-related adverse event was a spontaneous abortion. However, the rate of spontaneous abortion was 1.9 per million pregnant women. The authors concluded that they did not find any unusual pregnancy complications related to the women’s health or the fetus after flu vaccine administration (Source article).
Mitchelle Giles, with coauthors, conducted a systematic review of multiple studies involving in total over 100 000 pregnant women who received an inactivated flu vaccine.
Comparing to no influenza vaccination during pregnancy, the authors found evidence that the use of inactivated influenza vaccine is associated with a reduction in the incidence of low birth weight newborns, and no significant difference in the rate of stillbirth. They also found out that the use of the influenza vaccine is associated with a reduction in preterm births and no difference in congenital abnormalities in newborn babies (Source article).
Some parents are concerned about the presence of thimerosal (mercury) in vaccines, including a flu vaccine. Cristofer Price, with his colleagues, studied precisely that topic. They designed a case-control study consisting of 256 children with autism spectrum disorders and 752 control cases matched by birth year and gender. Using statistical methods and epidemiologic analysis, they concluded that there was no association between exposure to thimerosal in vaccines during pregnancy or after birth up to 20 months of age and the diagnosis of autism in a child (Source article).
If you are still worried about thimerosal in vaccines, most vaccines are available as a thimerosal-free single-dose vial, and you can ask to have that one given to you.
What is the effectiveness of the flu vaccine for pregnant women?
The overall effectiveness of the flu vaccine is not very high in the general population. The same is true for pregnant patients; however, it still provides significant protection. It may prevent or modify the course of disease in a mother. Additionally, we have data that infants who are born to mothers who received the flu vaccine require less frequent hospitalizations for their respiratory problems in early childhood.
A study of pregnant women who received the flu vaccine before the 2012-2013 flu season showed significant benefits for those women. Researchers looked at over 34 000 pregnant women and compared respiratory health outcomes of the group of pregnant women who received the flu vaccine to the group who did not. Women who did not receive the flu vaccine were three times more likely to seek help in the Emergency Room for respiratory sickness and two times more likely to be admitted to the hospital (Source article).
How else pregnant women can get protection from the flu?
Unfortunately, not everybody can get protection after being vaccinated for flu, and not all women get this vaccine while pregnant. During a bad flu season, many of us will get exposed and sick from the flu.
Due to the high risk for pregnant women, it is recommended by the CDC and ACOG that doctors prescribe post-exposure prophylaxis in such cases. If you are pregnant or delivered a baby within the last two weeks and you suspect that you were in contact with a person suffering from possible flu, call your doctor and ask what to do. Most likely, your doctor will prescribe you chemoprophylaxis. Chemoprophylaxis may include treatment with Oseltamivir (Tamiflu tablets by mouth) for ten days or using Zanamiver inhalations for ten days.
Chemoprophylaxis should not be delayed due to attempts to diagnose whether you or the person you were in contact with really have flu. Prophylaxis works well only when it is started early in the course of the disease.
What are the common symptoms of flu and when to contact your doctor?
Common symptoms of flu include:
- fever and chills.
- cough and sore throat
- muscle or body aches.
- extreme tiredness
- Gi symptoms such as vomiting and diarrhea
As you can see above, symptoms of flu are non-specific, and it would be difficult to differentiate between the flu virus and the common cold virus. If you are pregnant, you are at a much higher risk of developing more severe flu and its complication. Therefore you should never delay contacting your doctor if you think you are sick. Early chemoprophylaxis, such as administration of Tamiflu or secondary medication Zenamiver may be able to modify the course of your disease and decrease the chances of complications. Only your doctor will be able to decide if you should start taking anti-flu medications. In situations like that, conversation with your doctor, and discussion of all risks and benefits is a must.
I wrote also an article about parental worries regarding vaccinating their children. If you are interested in this topic you can find my article here.
This article is only for general information purposes. It should not be viewed as any medical advice. There is a chance that information here may be inaccurate. It would be best if you always discussed all health-related matters with your doctor before making any decisions that may affect your health or health of your family members.