During outbreaks of mumps, vaccine effectiveness is better when two mumps vaccinations are given rather than one, according to findings published in the current journal Pediatrics.
Despite high vaccination rates, an outbreak of mumps occurred in July 2005 among 541 children from the United States and abroad who attended a four- or seven-week overnight summer camp in upstate New York.
Dr. Joshua K. Schaffzin, of New York State Department of Health, Albany, and colleagues conducted a study of this outbreak.
Of the 541 children, 31 were diagnosed with mumps, for an overall attack rate of 5,7 percent.
Of the 507 children who had their immunisation history available, 440, including 16 who became ill, had received two doses of the mumps vaccine, for an attack rate of 3,6 percent.
Forty-six children, including four who became ill, had received one dose, for an attack rate of 8,7 percent. Of the 21 children who were not vaccinated, nine became ill, for an attack rate of 42,9 percent.
The researchers calculated the vaccine effectiveness to be 91,6 percent after two doses and 79,7 percent after one dose.
The two-dose vaccination, combined with correct diagnosis and strict control measures, is the best way to prevent and control outbreaks of mumps, Schaffzin commented in an interview with Reuters Health.
"These findings confirm that mumps disease is still prevalent and transmissible, and that the mumps vaccine continues to be effective," Schaffzin added. "Specific attention must be paid by medical professionals to correctly identify mumps infection when it occurs in their patients so as to curb spread of the virus."