ATLANTA — The Centers for Disease Control and Prevention's vaccine advisory panel recommended the use of either the combination measles-mumps-rubella-varicella vaccine or the separate MMR and varicella vaccines for children at 12–15 months of age, but to retain a preference for the MMRV vaccine for the second dose given at 4–6 years of age.
The issue was addressed by the Advisory Committee on Immunization Practices (ACIP) at its June meeting because data had emerged last year suggesting an increased risk for febrile seizures in very young children given MMRV, compared with children given the MMR and varicella vaccines separately. ACIP had previously stated a general preference for the use of combination vaccines over separate vaccines whenever possible, said Dr. Jonathan Temte, MMRV vaccine safety working group chair.
In a separate vote, ACIP qualified the language for that preference—contained in its general vaccine recommendations—to say that although combination vaccines are still “generally” preferred over separate injections of equivalent components, “considerations should include provider assessment, patient preference, and potential for adverse events,” along with other factors.
“In the era of the lowest levels of vaccine-preventable diseases, increasingly parents express more fear of vaccines than of diseases they prevent. Public trust in the safety and efficacy of vaccines is key to the success of immunization programs,” said Dr. Temte of the department of family medicine at the University of Wisconsin, Madison.
The MMRV vaccine—Merck & Co.'s ProQuad—is not on the U.S. market but is expected in 2010, a company spokesman said.
The American Academy of Pediatrics Committee on Infectious Diseases (COID) will take ACIP's vote into consideration, AAP liaison Dr. Joseph A. Bocchini Jr. said in an interview.
“The COID has not finished its deliberations on this. But, what this did was to remove the preference for MMRV. This now means the practitioner will have the opportunity, with the parents, to discuss the increased risk of febrile seizures associated with MMRV and make a provider/parent decision about whether to give two shots or one shot with a slightly increased risk.”
As to whether the COID—which Dr. Bocchini chairs—will come to the same conclusion, “I think it's possible they'll be in alignment, but I can't really say right now,” he said.
The vote on dose 2 was more straightforward, he noted. “The risk of febrile seizures in that age group is low…. So, under usual circumstances a combination vaccine would be preferred,” said Dr. Bocchini of Louisiana State University, Shreveport.
During the meeting, Dr. Karen Broder of the CDC's Immunization Safety Office presented a summary of evidence from two studies—one from the CDC's Vaccine Safety Datalink, the other from Merck—which together showed an approximately twofold elevated risk for febrile seizures among children aged 12–23 months in the 2 weeks following receipt of MMRV, compared with receipt of separate MMR and varicella vaccines. After vaccination, 7–9 febrile seizures occur per 10,000 children vaccinated with MMRV, compared with 3–4/10,000 with the separate vaccines.
After dose 1 of MMRV vaccine, 1 additional febrile seizure is expected to occur per approximately 2,300–2,600 children vaccinated, compared with when MMR and varicella vaccines are given separately, Dr. Broder said.
There was no increased risk for febrile seizure after dose 2, which is given to children at 4–6 years of age, although less information is available about the risk in that age group, she noted.
Committee members were divided on the dose 1 decision, with 4 of 14 members voting “no” to giving equal preference for the first dose, stating that they would rather see a preference for giving MMR and varicella vaccines separately. Among the concerns they raised were the need for storing all three vaccines, the need for scheduling additional visits, the extra time it would take to counsel parents about the risk of febrile seizures, and the fact that providers are paid two administration fees for giving the two separate shots.
But panel members who supported the vote for equal choice noted that although febrile seizures are scary to parents, most of these seizures are not of great medical consequence. A few panelists noted that expressing a preference for giving MMR and varicella separately would interfere with physician and patient choice, and might lead to decreased vaccine coverage because of the need for separate injections.
In other business, ACIP voted to apply these recommendations to children receiving the vaccines at ages other than those recommended, and to include the changes in the Vaccines for Children Program.
ACIP members who have conflicts of interest are required to abstain from voting.