Sandra Yin

May 14, 2012

May 14, 2012 (Baltimore, Maryland) — Adverse event rates for third-dose measles, mumps, rubella (MMR) vaccines were similar or lower than comparable rates seen in previous second-dose MMR vaccine research, according to results from a study presented here at the National Foundation for Infectious Diseases 15th Annual Conference on Vaccine Research.

"These findings suggest that a third dose of MMR vaccine administered in a school campaign as an outbreak intervention is safe, compared with first or second doses of MMR," said lead investigator Glen Abedi, BS, an epidemiologist at the Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia. The findings come from the first documented study to look specifically at adverse events related to a third dose of MMR vaccine, he added.

From June 2009 to June 2010, a mumps outbreak affected Connecticut, New Jersey, and New York in the United States; Quebec in Canada; and Israel. Orange County in New York accounted for 20% of the 3502 cases of mumps reported in the United States during that 12-month period. Even Orthodox Jewish communities with high vaccination coverage were affected.

In response to the outbreak, researchers designed a third-dose MMR intervention for school-aged children in an Orange County village who were enrolled in 1 of 3 religious schools. Collaborating with state and local health departments, they established vaccination clinics in each of the schools. From January 19 to February 2, 2010, they administered vaccines to sixth- through twelfth-grade students (mainly 11 to 17 year of age) with no history of mumps since July 1, 2009, and no history of 3 doses of vaccine that contained mumps.

Schoolwide, mumps rates dropped from 4.93 per 1000 in the preintervention period to 0.13 per 1000 in the postintervention period. Two months after the clinics, researchers distributed a survey to all students for self (or parent) reporting. The survey asked about adverse events experienced within 2 weeks of the vaccination. Follow-up surveys were completed by 1597 of the 1755 (91%) students who received the third dose. Students reported 115 adverse events, and 7.2% of respondents reported any adverse event. The most common adverse events were pain, redness, or swelling at the injection site (3.6%); joint or muscle aches (1.8%); and dizziness or lightheadedness (1.7%).

Researchers consulted 2 other data sources — the Vaccine Adverse Events Reporting System (VAERS) and physician reports — to gain a comprehensive understanding of adverse events in the intervention population. No adverse events were reported to VAERS at the time and location under study. Nor were any severe adverse events seen during physician follow-up.

Stanley Plotkin, MD, emeritus professor of pediatrics at the University of Pennsylvania and principal with Vaxconsult in Doylestown, Pennsylvania, noted during a discussion period that mumps immunity wanes even after the second dose. "The evidence that a third dose is well-tolerated is certainly welcome," he said.

He asked whether a routine third dose of MMR could be applied more broadly in areas with no mumps outbreak. Abedi said he thinks a larger study is needed. It's not clear how widely findings from the study can be applied outside the context of an outbreak, Abedi added.

The session moderator noted that someone who used to make national immunization recommendations was in the audience, and asked Walter Orenstein, MD, who directed the CDC National Immunization Program from 1993 to 2004, to weigh in.

Calling for a routine third dose of MMR is premature, Dr. Orenstein said. "Despite the increased incidence of mumps, it is still a relatively rare disease right now," he said. However, he said having a policy of routine revaccination during outbreaks "might be a reasonable policy."

Dr. Plotkin wanted to know whether it would make sense to ask Merck and GlaxoSmithKline to develop a monovalent mumps vaccine or whether it would be best to stick to the triple vaccine for the third dose.

According to Abedi, that is up for debate, but he noted that local physicians and health authorities seemed relieved that the outbreak was a mumps outbreak, not a measles or rubella outbreak, because the clinical manifestations of mumps are milder. "The third dose of MMR vaccine that we provided was actually welcomed by that community," he said, "because it provided protection."

Dr. Orenstein, who is also professor of medicine at Emory University School of Medicine and associate director of the Emory Vaccine Center in Atlanta, offered some historical context. "When we went to a second dose of MMR, we never had good evidence that we ever needed a second dose of rubella," he said. "But the feeling was that as long as we were taking the opportunity, we might as well give all 3 vaccines." He added that using different vaccines could cause confusion.

Mr. Abedi and Dr. Orenstein have disclosed no relevant financial relationships. Dr. Plotkin reports serving as an advisor or consultant for all major vaccine companies and many biotech firms; serving as a speaker or a member of a speakers bureau for all major vaccine companies and many biotechs; owning stock, stock options, or bonds from Dynavax, Inovio, and Hookipa; and holding a patent for and/or receiving royalties from a Merck & Co product.

National Foundation for Infectious Diseases (NFID) 15th Annual Conference on Vaccine Research: Session S29. Presented May 9, 2011.

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