On July 26, 2005, the Sullivan County Health Department (SCHD) and the New York State Department of Health (NYSDOH) were notified of a cluster of cases of parotitis among campers and staff members at a summer camp. An investigation conducted by NYSDOH identified 31 cases of mumps, likely introduced by a camp counselor who had traveled from the United Kingdom (UK) and had not been vaccinated for mumps. This report summarizes the results of the subsequent investigation by NYSDOH, which determined that, even in a population with 96% vaccination coverage, as was the case with participants in the summer camp, a mumps outbreak can result from exposure to virus imported from a country with an ongoing mumps epidemic.
http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5507a2.htm hmmmm - interesting bit here (from above site) : mumps vaccine effectiveness can be <85% in outbreak settings.
Both triggered by UK resident, too. I wonder if the strain is different?
edit to add: Also in 1990: "Between October 3 and November 23, 1990, clinical mumps developed in 54 students (attack rate, 18%), 53 of whom had been vaccinated. Most cases (40 <77%> of 52) occurred 12 to 20 days after a school-wide pep rally. "
and in 1983: From October 19, through December 14, 1983, 63 cases of mumps were reported from six schools in a school district in Atlantic County, New Jersey. These 63 cases are a 40% increase over the previous year's total of mumps among schoolchildren in the state.
. . . The index patient was a 12-year-old, unvaccinated, sixth-grade boy attending Elementary School A.
Forty-eight (76%) cases occurred in Elementary School A, for an overall attack rate of 5% (48/933). Twenty-five (52%) of these 48 cases occurred among the sixth grade students (Table 1). The attack rate in grade 6 (15%) was five times that in grades K-5 (3%) (p 0.001) (Table 1). . . Sixth graders were nearly seven times more likely to be susceptible to mumps than students in other grades (p 0.001) (Table 2).
Since initial reports suggested that many mumps cases occurred in children known to have been vaccinated, a vaccine efficacy study was done.* The sixth grade was used to estimate vaccine efficacy, because it represented 52% of the school's cases and had enough unvaccinated and vaccinated students to make calculation of attack rates in these two groups meaningful
. . . Vaccine efficacy was estimated to be 91% for sixth graders, with a 95% confidence interval of 77%-93% (Table 3). The attack rate in the vaccinated children in the sixth grade was 4% and fell within the 5%-10% primary vaccine failure rate observed in clinical trials (3).
. . .Since the attack rate for each grade was directly proportional to the percentage of unvaccinated students, the higher attack rate for sixth graders most likely reflected the fact that sixth graders were not covered by the law. Compliance with the law, as reflected in vaccine coverage rates, was greater than 95%. Thus, poor compliance with the school vaccination law did not lead to this outbreak. Rather, it was those grades not covered by the school law that provided the susceptibles that allowed the disease to spread.
http://www.cdc.gov/mmwr/preview/mmwrhtml/00000379.htm