IgG4ward! Good Question Series: Measles and the Measles Vaccine – What IgG4-RD Patients Need to Know

Information and Recommendations on Measles and the Measles Vaccine

The recent measles outbreak in parts of the United States has raised a number of questions among the IgG4-RD community regarding measles and the measles vaccine. In this Good Question! piece, we address:

• How to determine if you are adequately vaccinated against measles

• Whether you should consider getting a booster

• What to know if you're immunocompromised

• Where more information is needed

Understanding Measles Immunity

The first and most important point to understand is that if you were immunized as a child, you probably have good immunity to the measles and are likely at very low risk even in the chance – still rare – of a measles exposure.

Supporting Facts:

• In most states in the U.S., more than 90% of people have been immunized against measles. In some states, the percentage is higher than 95% (the light blue color in the map below), the level above which “herd immunity” is achieved. You can see the vaccination rate in your state in the map provided.

• Most people who were immunized since the late 1970s received two measles vaccines, providing excellent and long-lasting immunity to the virus.

• People who were immunized between 1957 and the late 1970s probably received just one dose. Fortunately, the measles vaccine used in that time frame – essentially the same one used now – was highly effective. Therefore, it is likely that the immunity of people vaccinated before the late 1970s is still good.

An Area of Unknown:

The current measles vaccine is based on a live but weakened strain of the virus -attenuated is the word used in the literature. Vaccines based on attenuated viruses are generally more effective than those based on killed viruses. This is simply because our immune systems recognize attenuated strains better than they do killed strains.

Between 1963 and 1968, some people were immunized with a killed vaccine. This vaccine may have been less effective. People immunized during this period should be extra-careful to ensure that their immunity to measles is intact. Below, we discuss how to do that.

Facts About the Measles Vaccine and IgG4-RD:

• The measles vaccine is given as part of the MMR vaccine-MMR = measles/mumps/rubella. The vaccine targets three formerly common childhood illnesses with one shot.

• As noted above, MMR is a live, attenuated This means that it should NOT be given to individuals who are immunocompromised because it is capable of causing active measles infections in individuals whose immune systems are weakened.

• People living with IgG4-RD may be immunocompromised if:

  • They are taking prednisone.

  • They are taking “disease-modifying anti-rheumatic disease drugs” (DMARDs) such as methotrexate, azathioprine, or mycophenolate.

  • They have received B cell depletion treatment (e.g., rituximab, ocrelizumab, obinutuzumab, inebilizumab) and have not had a return of B cell levels in the peripheral blood to normal levels.

  • They are actively receiving a medication that may suppress the function of B cells (e.g., obexelimab, rilzabrutinib), even if the medication does not deplete B cells.

People in any of these four categories should not receive the measles vaccine. Rather, they should discuss strategies for ensuring adequate immunity with their healthcare provider.

Recommendations:

• If you were immunized since the late 1970s, it is reasonable to assume that you are immune to measles.

• If you were immunized before the late 1970s and you are not potentially immunocompromised now (please see above), it is reasonable to get an MMR booster vaccine now.

• You can get an MMR booster at your local pharmacy without a doctor’s prescription. Call first to make sure the pharmacy has the vaccine on hand.

• You can get a good sense of whether or not your immunity to measles is intact by having your blood tested for measles IgG (IgG = immunoglobulin = an antibody. Measles IgG is an antibody to the measles virus). If you have antibodies to the measles virus, you are probably immune to infection.

• Knowledge of whether or not you have antibodies to measles would be helpful in planning treatment in the event that you are exposed to measles. For example:

• If you were immunized before the late 1970s and are potentially immunocompromised, it is reasonable to have your antibodies to measles tested in your blood. As described in the point above and illustrated by the figure below, this can be done by having your blood tested for “measles IgG”.

• Knowledge of whether or not you have antibodies to measles would be helpful in planning treatment in the event that you are exposed to measles. For example:

  • If you have measles antibodies, there is a good chance that your immunity to measles is intact and that you are unlikely to contract measles even if exposed to a person with an active infection.

  • If you do not have antibodies to measles, it is important to know that, too. Treatment that may prevent an active infection is available. This medication is known as intravenous immune globulin (IVIg). IVIg should be administered quickly if you do not have immunity to the measles virus and have been exposed to a person with an active infection.

Knowledge of your measles antibody status in advance of any potential exposure to measles can be extremely helpful in planning what to do if you are exposed.

Below is a photo of the measles IgG results of a person vaccinated in 1964 who still has a very robust amount of antibodies to measles and is presumed to be immune: