ACIP Now Recommends Third Dose of Mumps Vaccine

Marcia Frellick

January 11, 2018

A third dose of measles, mumps, rubella (MMR) vaccine is now recommended for people previously vaccinated with two doses who are identified as being at higher risk for mumps because of an outbreak, according to the Advisory Committee on Immunization Practices (ACIP).

The recommendation, which comes in light of a substantial increase in mumps outbreaks since 2015, was published online today in the Centers for Disease Control and Prevention's Morbidity and Mortality Weekly Report.

Mona Marin, MD, from the Centers for Disease Control and Prevention's Division of Viral Diseases, National Center for Immunization and Respiratory Diseases, and colleagues say the third dose may be administered as MMR or the measles, mumps, rubella, and varicella (MMRV) vaccine.

Mumps cases in the last 2 years are the highest in a decade, with 6369 cases in 2016 and 5629 (preliminary) in 2017.

From January 1, 2016, through June 30, 2017, state health departments reported 150 mumps outbreaks, defined as three or more cases in one place, which account for 9200 cases. Half the outbreaks (50%) occurred in universities, and 11% occurred in in close-knit communities.

Among the 9200 people infected during an outbreak, 70% had received two MMR doses before developing mumps.

Efficacy evidence for the third dose comes from three epidemiological trials, the authors report. "Incremental vaccine effectiveness of the third versus the second MMR dose in these studies ranged from 61% to 88%, with one estimate being statistically significant (78.1%, 95% confidence interval = 60.9%–87.8%). This study also found that students who had received 2 doses of MMR vaccine ≥13 years before the outbreak had nine or more times the risk for contracting mumps than did those who had received the second dose within the 2 years preceding the outbreak."

Because mumps outbreaks are complex, according to the Centers for Disease Control and Prevention, public health authorities should advise parents, students, healthcare providers, and universities on who should get the third dose and when.

ACIP determined that the available evidence shows a third dose has at least short-term benefits in case of outbreaks, no serious adverse effects, and low rates of minor adverse effects.

Among young adults who received the third dose, prevalence of 4 symptoms was higher in the first month postvaccination than prevaccination: lymphadenopathy (12%), diarrhea (9%), headache (7%), and joint pain (6%). The episodes lasted an average 1 to 3 days.

However, the benefit of the third dose outweighs risk of minor adverse effects, ACIP concluded. Those who should not receive the third dose are the same contraindicated in current guidance for 1 or 2 doses.

The recommendation is a supplement to the 2013 recommendations, and does not change procedure for the general public.

"The current routine recommendation for 2 doses of MMR vaccine appears to be sufficient for mumps control in the general population," the authors write.

The authors have disclosed no relevant financial relationships.

Morb Mortal Wkly Rep. 2018;67:33-38. Full text

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