[An epidemic outbreak of mumps. A study of vaccinal efficacy].

OBJECTIVE

Description of an outbreak of mumps in an urban area. Study of the effectiveness of the mumps component of the triple virus (TV) vaccination.

DESIGN

Cross sectional descriptive study of the outbreak. The cases were obtained from the Andalusian Register of Infectious Diseases (SVEA in Spanish). The effectiveness of the vaccine was studied through a retrospective cohort design, with the cohorts defined according to their vaccination history.

SETTING

Urban area of low social class and income and young population pyramid. The outbreak occurred between March and November 1997. The effectiveness of vaccination at one school was studied. PATIENTS AND OTHER PARTICIPANTS, RESIDENTS IN THE AREA: The source of the population was the 1996 municipal census.

INTERVENTIONS: The declared cases of mumps were taken from the SVEA. The state of vaccination was documented through a review of the school registration records, vaccination cards and the health centre register of names.

MEASUREMENTS AND MAIN

RESULTS

A total of 283 cases of mumps were declared. There were more cases in the 0-10 age group than at older ages. 79% of cases were vaccinated (95% CI, 74.3-73.7). Effectiveness of a dose of the mumps component of the vaccine was low (46%; CI, 0-84), though the effectiveness of a second dose was higher (87%; CI, 27-99).

CONCLUSIONS

The low effectiveness of the mumps component of the TV vaccination was confirmed. It is proposed that the age for the second dose should be brought forward to school-starting age (primary, first year). Ensuring school vaccination is recommended.