Effectiveness of a vaccination program against mumps in Ukraine.

Medical records and incidence data were analyzed retrospectively to document the epidemiology, clinical features, and outcomes of mumps in relation to vaccination status in the Lviv province of Ukraine over a 7.5-year period, beginning in 2000, when a second dose of mumps vaccine was introduced. Lviv, 1 of 27 provinces in western Ukraine, with a land area of 21,833 km(2), had a total population of about 2,555,834 in 2006. The initial success of the second dose introduction in 2000 in Ukraine was limited by a local outbreak of mumps in Lviv province in 2000-2002 due to a vaccine shortage; most cases were over the age of 7 years. The vaccine with the Leningrad-3 virus strain used before 2001 was then replaced by the triple vaccine "Priorix", with the RIT 4385 derivate of the Jeryl Lynn strain, Belgium. Orchitis and aseptic meningitis were associated with the Russian vaccine. Of the 10,894 reported cases, the most severe (367 cases, 3.4%) were hospitalized in the Lviv Hospital for Infectious Diseases. Admitted patients were predominantly male and over 14 years old. Of the 367 patients admitted to the Lviv Hospital for Infectious Diseases, 45.8% had been vaccinated (mostly by a first dose of Russian vaccine), 15.9% had not been vaccinated, and 38.1% had an unknown vaccination status. More mumps cases occurred in winter and spring than in summer and autumn. The clinical picture and complications (orchitis, pancreatitis, meningitis, and encephalitis) were typical of this disease. The vaccine shortage and an increase in the susceptible population among those who received the Russian vaccine contributed to the outbreak. The use of vaccine with a derivate of the Jeryl Lynn strain has resulted in a dramatic drop in mumps cases since 2002.