The MMR vaccine should not be given to anyone who has had a severe allergic reaction to a previous dose of the vaccine or to any component in the vaccine, including gelatin or the antibiotic neoourcin. In addition, people who are moderately or severely ill should be cautioned against receiving this vaccine until they recover from their illness.
Pregnant women should wait until after their pregnancy to receive the vaccine to avoid the theoretical risk of infecting the fetus with the live virus. Women who are not pregnant should wait until at least four weeks after receiving the MMR vaccine before becoming pregnant.
Because the vaccine contains a live, attenuated virus, it is not recommended for any person with a deficiency of the immune system. This would include anyone who has HIV or certain kinds of cancer, is receiving chemotherapy or radiation therapy, or has been on medications that suppress the immune system, such as steroids, for more than two weeks.
People who have a history of a low platelet count should discuss with their doctors the risks and benefits of receiving the MMR vaccine because one of the rare side effects of the vaccine is to lower a recipient’s platelet count.
People who have received a blood transfusion or other blood products, such as immune globulin, should usually wait before receiving the MMR vaccine. The waiting period ranges from three to eleven months, depending on the type and volume of blood products received.