Abstract
The mumps outbreak in the Plzeň Region in 2011 was analysed retrospectively using the epidemiological, clinical, and laboratory data. Vaccine efficacy analysis was also conducted in various population groups.
In 2011, 721 mumps cases were reported in the Plzeň Region (incidence: 126.1 cases per 100 000 population). The average patient age was 19.4 years, with a median of 18 years (age range 1-77 years).
Four hundred and seventeen (57.8%) patients were males. Biological specimens from 375 (52.0%) patients were investigated serologically in the virology laboratory and mumps were laboratory confirmed in 316 (43.8%) of them - in 222 patients, one blood specimen was analysed.
The most afflicted area was the Klatovy district with the incidence of 449.3/100 000 population. The most affected age group were 15-19 year-olds with the incidence of 1008.2/100 000 population.
Forty-two (5.8%) patients were diagnosed with complications and 68 (9.4%) patients were admitted to the hospital. No statistically significant difference was found in the incidence of complications between the vaccinated and non-vaccinated patients.
The assessment of hospitalisation risk showed a statistically significant difference between the vaccinated and non-vaccinated persons in both the whole study cohort and subcohort of patients who received the mumps vaccine within the childhood immunization schedule (p = 0.000 and p = 0.004, respectively). The average age of the vaccinated patients was 16.1 years (median of 17) and that of the non-vaccinated patients was, 29.3 years (median of 27).
At the six to ten-month interval, as laid down by the legislation, the second dose of the vaccine was only given to 83.6 % of the patients. The screening method showed a high efficacy of the vaccine in the age group 20-25 years (97.6% in two-dose recipients), declining to 29.6% in the most affected age group of 15-19 years.