Measles, mumps, and rubella: monitoring in Switzerland through a sentinel network, 1986-94. Sentinella Arbeitsgemeinschaft.

STUDY OBJECTIVES

Since 1986, the national sentinel network in Switzerland (Sentinella) has collected reports of measles, mumps, and rubella cases in order to evaluate the impact of the Swiss MMR vaccination campaign (started in 1987) on disease frequency.

DESIGN

Passive surveillance of clinical measles, mumps, and rubella cases through a voluntary physician based sentinel network in Switzerland.

SETTING

Each year between June 1986 and May 1994, 150 to 200 general practitioners, specialists in internal medicine, and paediatricians in private practice covering the whole country have reported weekly numbers of consultations.

PATIENTS

Every patient who fulfilled the case definition and consulted a physician participating in the Sentinella network was reported.

MAIN RESULTS

Since 1986, the annual number of reported measles cases per physician has fallen--from 1.3 (95% confidence interval (CI) 1.11, 1.50) in 1986-87 to 0.4 (95% CI 0.30, 0.50) in 1993-94. A decreasing trend, although less pronounced, was also observed for rubella. An initial decrease in mumps cases was reported--from 1.8 (95% CI 1.57, 2.03) annually reported cases per physician in 1986-87 to 0.7 (95% CI 0.55, 0.83) in 1989-90. This was followed, however, by a net and sustained increase. In 1993-94, the mean annual number of reported mumps cases per practitioner reached 4.7 (95% CI 4.34, 5.01) which was the highest level since surveillance had started. Over the whole eight year period, reported mumps cases, in terms of the percentage of consultations, were four times more frequent in the French speaking part of Switzerland than in the rest of the country. The proportion of mumps cases in people reported to have been vaccinated also increased--from 10% in 1986-87 to 60% in 1993-94.

CONCLUSIONS

Reductions in cases of measles and rubella but an appreciable increase in mumps cases have been observed in the past three years in Switzerland. This findings, combined with increasing vaccination coverage and the fact that 60% of mumps cases are reported in vaccinated people, suggests that the overall efficacy of the mumps vaccines used in Switzerland is probably below 80%. Under these conditions the goal of eliminating mumps will probably not be reached. Further studies are needed to evaluate the efficacy of the different mumps vaccines used.