(See also Dr. Frank’s earlier statement and information about the Measles Outbreak.)
The recent measles outbreak has obviously created anxiety and spurred many questions. Here are the answers provided to some of the most common questions by Drs. Bal, Frank and Liu, Infectious Diseases consultants at Jersey Shore University Medical Center. Of course, every case is different and specific questions should be addressed to your primary care physician.
- My child is 3 years of age. He has received one dose of measles vaccine. Should he receive his second dose early? What if we are traveling to Israel?
- Children under 4 years of age are considered protected with one dose of vaccine given after their first birthday. They should receive a second dose only if the first dose was given before their first birthday. Children 4-6 years of age should receive their second dose of MMR now.
- If the child is up to date with measles vaccination according to their age then they are considered protected
- How effective is the Measles vaccine
- Serum antibodies develop in approximately 95% of children immunized after 12 months of age and 98% of children immunized at 18 months of age with a single dose of measles vaccine. More than 99% of children develop measles immunity after immunization with two doses of measles vaccine given after 12 month of age, at least 4 weeks apart
- We are planning a trip to Israel with our 8-month old who has received one dose of MMR. Will she be protected? Are there increased risks on an airplane?
- Measles vaccine is recommended for children between 6-11 months of age during community outbreaks or when infants between 6-11 months of age are travelling to an area where measles transmission has been documented.
- The immune response to measles vaccine in children less than one year old is significantly lower and the infant may not be protected if exposed to measles. In the event of an exposure, gamma globulin should be administered within 6 days.
- Airplanes recirculate air. Measles can be transmitted to susceptible individuals on a plane only if another passenger has a case of measles.
- I know that I was fully immunized with two doses of measles vaccine. I am currently taking immunosuppressive medication. What are my risks? Should I do anything now?
- In general. most patients who were immune—either because they were born before 1957 and had measles or because they have been fully immunized—will remain protected despite most immune suppression. Severe immune suppression—like a bone marrow transplant—may reduce that immunity. It would be prudent for those with significant immune suppression to minimize contact with large groups that may include sick people.
- If in doubt about immunity, then measure serum antibodies for measles. The presence of antibodies will confirm immunity. The absence of antibody means one may be susceptible and gamma globulin would be recommended for any exposure.
- My child, who had received one dose of measles vaccine, had a definite exposure to measles. A second dose of vaccine was given within 24 hours. One week later, he developed an ear infection and fever to 103 degrees F. A nasopharyngeal swab was performed and was reported positive for measles. Is it positive from the vaccine or from measles?
- There are two main ways to test for measles in the laboratory: serology and Real-Time Polymerase Chain Reaction (RT-PCR). Serology refers to the measurement of antibodies to the virus. Antibodies are our body’s way of fighting the virus and preventing re-infection. All vaccines are designed to mimic infection and therefore “trick” the body into forming antibodies to prevent infection. Serology therefore cannot distinguish between actual measles and an effect of the vaccine. PCR is a way of looking for the actual RNA of the virus and is the test done on the nasopharyngeal swab. The test is more specific than serology but there still may be cross-reactions between vaccine strains of the virus and wild-type virus unless more sophisticated analysis is performed. Therefore, based on the information provided, we cannot be sure if the test reflected a mild case of the measles or was due to immunization.
- I was born in 1952 and my measles titers are negative. Am I immune to measles? Do I need a booster? I was born in 1977 and had two -doses of MMR but my titers are negative. Do I need a booster?
- Anyone with natural immunity to measles (people born before 1957) or who definitely had two doses of measles vaccine is considered protected. That protection is at least 97% and the few cases that may break through are generally mild and less contagious.
- Verbal reports of vaccination should not be accepted unless supported by written documentation of vaccination. If uncertain, then revaccination is warranted.
- A booster vaccination is not recommended for those who already have immunity confirmed.
- How long does it take the vaccine to take effect?
- It may take up to 2 weeks to fully develop protective antibody after measles vaccination. However, if an individual is exposed, a single dose of MMR administered within 3 days of exposure is likely to prevent measles.
- Everyone in my family is immunized. Should I allow my children to play with children who have not been immunized?
A. Yes, your children are safe. The unimmunized children are at risk. If a child is not immunized because he or she unfortunately has a medical problem that precludes immunization, we hope that that child is protected by “herd immunity” meaning that if the vast majority of children are immune, transmission is not likely to occur in a community. This herd immunity fails when parents willfully choose not to vaccinate their children putting their children at risk but also endangering the lives of those children who have illnesses that preclude immunization.
- My child has a medical contraindication to immunization. What precautions should I take?
- At this point, as the outbreak appears to be relatively small, it appears reasonable to have your child continue with most normal activities, though it is likely that he or she will be asked not to attend school or play groups. You should make sure playmates were immunized more than 21 days ago. If the unimmunized child is exposed to measles, gamma globulin should be administered within 6 days of exposure.
- What is the difference between the vaccine and gamma globulin?
- A vaccine contains either a dead or a weakened form of the virus or a synthetically made fragment of the virus. When the body “sees” the vaccine, the immune system starts to build antibodies to fight the virus. This protection is often long lasting (e.g. measles) but may wane over time (e.g. tetanus) thus requiring booster doses of vaccine. Gamma globulin contains pre-formed antibodies that last only a short time. In the case of measles, the vaccine is highly effective in preventing the disease. Gamma globulin will lessen the severity.