ACIP Approves Revised MMR Recommendations

Diana Mahoney

October 29, 2012

The Advisory Committee on Immunization Practices (ACIP) of the Centers for Disease Control and Prevention (CDC) has voted unanimously to approve changes to the current measles, mumps, and rubella (MMR) vaccine recommendations pertaining to individuals with HIV infection, evidence of immunity, and measles postexposure prophylaxis with immune globulin (Ig).

With respect to the HIV-infected population, MMR vaccination is currently recommended for all asymptomatic HIV-infected individuals who do not have evidence of severe immunosuppression, and consideration is advised for all symptomatic HIV-infected individuals without evidence of severe immunosuppression.

According to an assessment of the available evidence suggesting that effective antiretroviral therapy (ART) does not reliably restore immunity to previous vaccinations, the proposed changes include a recommendation for revaccination in individuals with perinatal HIV infection who were vaccinated before effective ART, Huong McLean, PhD, MPH, from the CDC's National Center for Immunizations and Respiratory Diseases, reported at the October 24 meeting of the ACIP on behalf of the MMR Vaccine Work Group.

The proposal also recommended removing the distinction between asymptomatic and symptomatic HIV infection in the guidance document and changing the timing of the 2 MMR doses.

"All persons with perinatal HIV infection who do not have current evidence of severe immunosuppression who were initially vaccinated prior to effective ART should receive 2 appropriately spaced doses of the MMR vaccine once effective ART has been established, unless they have other acceptable current evidence of MMR immunity," Dr. McLean stated.

The first MMR dose should be administered at age 12 to 15 months, and the second at age 4 to 6 years or as early as 28 days after the first dose, according to the work group recommendation, Dr. McLean said. She also noted that the goal of the revised strategy is to cover adolescents and young adults who received MMR vaccines before effective ART.

"The concern is that these individuals lack protection from measles due to a combination of primary vaccine failure or waning response over time. They are unlikely to have high levels of immunity, despite a good response to ART, if they are not revaccinated," Dr. McLean said.

Because ART is initiated routinely in infants with born with HIV, their immune response to the MMR vaccine is expected to be similar to that of uninfected children, she added. "For the same reason, a second dose of the MMR vaccine at 4 to 6 years is also recommended for these children."

With respect to the acceptable evidence of immunity, which was developed to guide vaccination assessment and administration, the work group proposed adding "laboratory confirmation of disease" to the presumptive evidence criteria for measles and mumps and removing "physician diagnoses of disease." The low validity of history over the last 30 years and the challenges associated with documenting history for physician records prompted this revision, according to Dr. McLean.

Changes to the current recommendations for measles postexposure prophylaxis address the needs of specific populations in whom the risk for complications from measles is increased, including infants aged 12 months and younger, pregnant women without evidence of measles immunity, and immunocompromised individuals.

In the case of measles exposure, "these at-risk groups should receive Ig," Dr. McLean stressed. "[Intramuscular Ig] IMIg can be given to other persons who do not have evidence of measles immunity, but priority should be given to persons exposed in settings with intense prolonged close contact, such as households, daycares, and classrooms," she said.

The proposed recommended dose of IMIg is 0.5 mL/kg of body weight (maximum 15 mL), and the proposed recommended dose of intravenous Ig (IVIg) is 400 mg/kg.

Infants aged 12 months and younger who are exposed to measles are at a higher risk for severe disease and complications, particularly if their mother is nonimmune or their maternal antibodies to measles have waned, and as such should be given IMIg.

"The MMR vaccine can be given in place of IMIg for infants aged 6 to 11 months if administered within 72 hours of initial exposure," Dr. McLean said.

The proposed recommendations for the use of IG postexposure prophylaxis in pregnant women without evidence of immunity suggest the administration of IVIg. In addition, severely immunocompromised individuals who are exposed to measles should receive IVIg prophylaxis regardless of immunologic or vaccination status "because they may not be protected," Dr. McLean stated.

This includes HIV-infected individuals of all ages with CD4 cell count percentages of less than 15% and those older than 5 years with CD4 cell counts lower than 200 cells/mm3, as well as those who have not received the MMR vaccine since initiation of effective ART.

"For those already receiving IVIg therapy, a minimum 400 mg/kg dose within 3 weeks prior to measles exposure should be enough to prevent measles infection," Dr. McLean said. For patients' subcutaneous Ig therapy, "administration of at least 200 mg/kg body weight for 2 consecutive weeks before measles exposure should be sufficient."

The work group also considered the possibility of a 3-dose MMR strategy to stem the tide of large mumps outbreaks that have occurred despite high 2-dose MMR vaccine coverage in some parts of the world, but they determined that the data are insufficient at this time to recommend for or against the use of a third dose for outbreak control, Dr. McLean said.

The revised recommendations will be published in the CDC's Morbidity and Mortality Weekly Report on acceptance by the director of the CDC and the secretary of Health and Human Services, according to Jonathan Temte, MD, PhD, chair of the ACIP and of the MMR Vaccine Work Group.

Dr. McLean and Dr. Temte have disclosed no relevant financial relationships.