How Do Vaccines Work?
Tiny organisms that invade the body cause infections that can make you ill. When you get an infection, your body fights these organisms and builds a special defense (antibodies) against them. In many cases, once your body has created this defense, you become immune to that type of infection and will not be made ill by it again in the future.
Vaccines usually contain a small amount of the organism that causes an infection. In general, the vaccine contains just enough of the organism to help your body defend against the infection, but not enough to make you sick. In this way, vaccinations allow you to become immune to an infection without having the illness first.
There are two kinds of vaccines:
- Those that contain a live organism
- Those that contain an organism that has been inactivated
Generally, live-virus vaccines are not recommended for pregnant women.
When Should a Vaccination Be Considered?
The best time to talk about vaccinations is during a visit with your health care provider before you get pregnant. Before pregnancy, you can get vaccinations that will protect you and your baby during pregnancy.
Some infections can harm your baby if you are exposed to them while you are pregnant. But in some cases, the vaccine that prevents the infection may also be harmful. In many cases, experts don't know whether it is riskier to get a particular vaccine or not.
While you should avoid unnecessary risks during pregnancy, you also don't want to open the door to any illnesses that may have dangerous consequences for both you and your baby. This is why it's very important to talk to your health care provider about vaccinations.
No vaccine is completely safe or 100% effective. Your health care provider may tell you that the benefits of getting vaccinated outweigh potential risks if all of the following are true:
- You are very likely to be exposed to a particular infection.
- The infection would pose a serious risk to you or your baby.
- The vaccine is unlikely to cause harm to you or your baby.
If you are at an increased risk for infection, your doctor may suggest that you receive a vaccination that generally isn't recommended during pregnancy. Here are some examples of people who are often at increased risk of infection:
- Those who work in health care facilities
- Those who are traveling to areas where the infection is common
Discuss each vaccine with your health care provider on a case-by-case basis. Carefully weigh the risks and benefits of the protection that the vaccination will provide.
If you became pregnant within four weeks after your last vaccination, talk to your health care provider about whether or not the vaccination may affect the baby.
Recommended Vaccinations
According to the U.S. Centers for Disease Control and Prevention (CDC), the following vaccines are routinely recommended for pregnant women who are at risk of infection:
- Hepatitis B: Recommended for pregnant women at risk of infection.
- Influenza (flu shot made with an inactivated virus): Recommended for women who will be pregnant during the flu season.
- Tetanus/Diphtheria: Routinely recommended for pregnant women.
- Meningococcal: Recommended for pregnant women at risk of infection.
- Rabies: Recommended for those exposed to infection. May be recommended for those at a high risk of exposure.
Vaccinations You Should Avoid
According to the CDC, the following live-virus vaccines are not recommended during pregnancy:
- LAIV (live, attenuated influenza vaccine) flu shot: Women who are pregnant during flu season should be inoculated with the inactivated version of the vaccine instead.
- Measles*
- Mumps
- Rubella (German measles)*
- Varicella (chickenpox) *
- BCG (tuberculosis) *
Special Cases
Experts know little about how the following vaccinations may affect your baby:
- Hepatitis A
- Pneumococcal vaccine
- Polio (IPV)
- Anthrax
- Japanese encephalitis
- Typhoid
- Vaccinia (smallpox)
- Yellow fever
You and your doctor should carefully weigh the risks and benefits of using these vaccines during your pregnancy.
*If possible, women should avoid becoming pregnant for one month after vaccination. If you are not vaccinated because you are currently pregnancy, talk with your health care provider about the possible risks.
