MEASLES, MUMPS, AND RUBELLA - MONITORING IN SWITZERLAND THROUGH A SENTINEL NETWORK, 1986-94

Study objectives - Since 1986, the national sentinel network in Switze rland (Sentinella) has collected reports of measles, mumps, and rubell a cases in order to evaluate the impact of the Swiss MMR vaccination c ampaign (started in 1987) on disease frequency. Design - Passive surve illance of clinical measles, mumps, and rubella cases through a volunt ary physician based sentinel network in Switzerland. Setting - Each ye ar between June 1986 and May 1994, 150 to 200 general practitioners, s pecialists in internal medicine, and paediatricians in private practic e covering the whole country have reported weekly numbers of consultat ions. Patients - Every patient who fulfilled the case definition and c onsulted a physician participating in the Sentinella network was repor ted. 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 decr easing 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 s ustained increase, In 1993-94, the mean annual number of reported mump s 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 ye ar period, reported mumps cases, in terms of the percentage of consult ations, were four times more frequent in the French speaking part of S witzerland than in the rest of the country. The proportion of mumps ca ses in people reported to have been vaccinated also increased - from 1 0% in 1986-87 to 60% in 1993-94. Conclusions - Reductions in cases of measles and rubella but an appreciable increase in mumps cases have be en observed in the past three years in Switzerland. This finding, comb ined with increasing vaccination coverage and the fact that 60% of mum ps cases are reported in vaccinated people, suggests that the overall efficacy of the mumps vaccines used in Switzerland is probably below 8 0%. Under these conditions the goal of eliminating mumps will probably not be reached. Further studies are needed to evaluate the efficacy o f the different mumps vaccines used.