(HealthDay News) – A mumps outbreak largely among vaccinated, Orthodox Jewish male adolescents may have been transmitted by intense exposure, particularly among boys in schools.

Albert E. Barskey, MPH, from the U.S. Centers for Disease Control and Prevention in Atlanta, and colleagues describe the features of a mumps outbreak (3,502 cases) which occurred from June 28, 2009–June 27, 2010, in New York City, two upstate New York counties, and one New Jersey county.

The researchers found that 97% of case patients were Orthodox Jewish and were disproportionately adolescents (age 13–17 years) and males (78% of patients in that age group). Of those whose mumps vaccination status was known, 89% had received two doses of a mumps-containing vaccine and 8% had received one dose. Transmission was focused within Jewish schools for boys, where students study intently for hours daily in face-to-face interactions with other students. The most common complication was orchitis, the rate of which was significantly higher among unvaccinated individuals than those who had received two vaccine doses.

“The epidemiologic features of this outbreak suggest that intense exposures, particularly among boys in schools, facilitated transmission and overcame vaccine-induced protection in these patients,” Barskey and colleagues conclude. “High rates of two-dose coverage reduced the severity of the disease and the transmission to persons in settings of less intense exposure.”

Full Text (subscription or payment may be required)