MMR

• Risk factors: Allergic reaction to other vaccines | Severe allergy to eggs or egg products (MMR II only) | Allergy to rubber or latex (Priorix only)

As with any vaccine, there's a rare chance that your child might have a severe allergic reaction to MMR vaccine. In particular, people with a severe allergy to eggs or egg products shouldn't receive MMR II because it can contain egg protein. Additionally, people with an allergy to latex should also be careful when receiving Priorix since the cap of the prefilled syringe is made of latex. If it's your child's first dose, your provider will typically ask you and your child to stay at the pharmacy or clinic for a short period of time after they've received their vaccine. This is to make sure your child gets proper care in case of a serious allergic reaction. Sometimes, these reactions can happen after you've already left the clinic. Get medical help right away if your child has symptoms such as feeling faint, face swelling, tightness in your throat, difficulty breathing, hives, rash, dizziness, shaking, nausea, or chest pain.

• Risk factors: History of febrile seizure | Family history of febrile seizures

Although rare, MMR vaccine can put your child at risk for fever with seizures within the first 2 weeks after they've received the vaccine. Let your child's provider know if they've ever had a febrile seizure or have a family history of febrile seizures before getting MMR vaccine, you'll need to be careful and monitor your child for fevers and get medical help if needed.

• Risk factor: History of a drop in platelet count after receiving MMR vaccine

MMR vaccine can lower your child's platelet count temporarily. In people who received MMR II, this usually happens 4 to 6 weeks after injection. Platelets are cells in your blood that form clots to stop you from bleeding. A low platelet count raises your child's risk for severe bleeding. For most people, this temporary drop in platelet count won't cause problems. But if your child already has low platelet count because of a medical condition, this can put them at higher risk for bleeds. Get medical help if your child has symptoms such as difficulty stopping a bleed, bruises that don't go away, or feeling lightheaded, dizzy, or confused.

• Risk factor: Weakened immune system from medical conditions or medications

People with weakened immune systems should avoid MMR vaccine. This is because you or your child might get seriously sick from the weakened, but active viruses in the vaccine. People with weakened immune systems include those with certain medical conditions (e.g., human immunodeficiency virus (HIV) or cancer) and those taking medications that can weaken the immune system (e.g., high-dose corticosteroids or transplant medications). If you or your child has a family history of immunodeficiency (poor immune system function), you'll need to check with your or your child's provider about other vaccine options. Make sure to tell your healthcare providers about you or your child's medical history before receiving MMR vaccine.

MMR vaccine shouldn've be used by people who are pregnant. Even though this vaccine contains weakened forms of the measles, mumps, and rubella viruses, there's still a possibility that pregnant people can get infected from the vaccine. If this happens, the viruses can cause birth defects, premature birth, or death to the unborn baby. If you're already pregnant, wait until after you give birth to get MMR vaccine. If you're thinking of becoming pregnant, avoid getting pregnant for at least a month after you get this vaccine. Talk with your provider if you have any questions about MMR and pregnancy.