Mumps Outbreak Affects More than 1,500 in New York, New Jersey

An outbreak of mumps in New York and New Jersey has expanded to more than 1,500 reported cases, and the CDC is reminding physicians that outbreaks can occur even in communities with high two-dose coverage of the measles, mumps and rubella -- or MMR -- vaccine.

The agency also said in a Feb. 12 Morbidity and Mortality Weekly Report that mumps cases should be reported promptly to public health officials.

The mumps outbreak, which is the largest in the United States since 2006, began after an 11-year-old boy returned from a trip to the United Kingdom, which had more than 7,000 laboratory-confirmed cases of mumps last year.

The boy attended a summer camp for tradition-observant Jewish boys in New York, where he became symptomatic on June 28. Other campers and staff also became ill, and transmission continued when attendees returned home.

Of the 1,521 cases reported as of Jan. 29, less than 3 percent occurred among persons outside the tradition-observant Jewish community. The CDC said high vaccination coverage in surrounding communities likely prevented other outbreaks.

However, vaccination coverage in the affected community was not low. The CDC said that among patients for whom vaccination status was reported, 88 percent had received at least one dose of mumps-containing vaccine, and 75 percent had received two doses.

The CDC said studies have estimated the effectiveness of the mumps vaccine to be from 73 percent to 93 percent after one dose and from 79 percent to 95 percent after two doses.

The agency said that although vaccination alone does not prevent all mumps outbreaks, maintaining high MMR coverage is the most effective way to prevent outbreaks and to limit their size when they do occur. The agency said that since the current mumps vaccine was licensed in 1967, the number of cases reported annually has fallen from 186,000 to an average of fewer than 500.

The CDC's Advisory Committee on Immunization Practices and the AAFP recommend that children (1-page PDF; About PDFs) receive two doses of MMR, with the first dose administered at age 12-15 months and the second dose at age 4-6 years. During outbreaks, a second dose of vaccine is recommended for children ages 1 to 4 years.

Adults at high risk for disease -- including people who work in health care facilities, international travelers and college students -- also are recommended (2-page PDF; About PDFs) to receive two doses. Health care workers born in 1957 or later without laboratory evidence of immunity should receive two doses, and those born before 1957 without laboratory evidence of immunity should consider receiving one dose, the CDC said.

No deaths have been linked to the ongoing outbreak, but there have been 19 hospitalizations. The CDC said there have been 65 reports of complications from mumps: orchitis (55 cases), pancreatitis (five cases), aseptic meningitis (two cases), transient deafness (one case), Bell's palsy (one case) and oophoritis (one case).