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Information is extremely important for immunisation programmes. The information should be clear, transparent, easily accessible and adapted to the different target populations. Parents consider the information presently available to be insufficient. This constitutes an obstacle to the introduction of universal vaccination against Hepatitis B in Switzerland. The population groups targeted by the information have to be the public health authorities, physicians, adolescents, parents and teachers. Various documents are now available or in preparation and should allow an effective discussion between these different partners.

The Swiss Federal Office of Public Health and the Advisory Board on Immunisation recommended that all adolescents aged 11 to 15 should be vaccinated against hepatitis B in December 1997. The introduction of universal immunisation is justified for epidemiological and economical reasons. Universal immunisation in no way excludes the immunisation of all persons exposed to a specific risk and the prenatal screening and immunisation of exposed newborns. Hepatitis B vaccines are safe and highly effective. The main reasons for this recommendation are summarised in the article.

With the introduction of a vaccine against hepatitis B in the early 1980s, a vaccination strategy targeted at high risk groups was implemented in most developed countries. Although such a strategy is efficient on an individual basis, it has been shown that it only has a limited impact on the overall rate of infections in the population. Public health authorities were therefore prompted to additionally recommend a universal vaccination strategy to reduce and ultimately eliminate hepatitis B infections. The option to primarily vaccinate infants, adolescents or both age groups depends on the epidemiological situation of a country, the availability of organisational facilities, financial resources and acceptability. Combining a targeted and a universal vaccination strategy provides the optimal protection against hepatitis B, both at an individual and population level.

Hepatitis B is transmitted by three main routes: contact with blood and body fluids, sexual contacts, and perinatally from the infected mother to her newborn baby. Horizontal transmission within the household of an infected person is common, especially in families with infants. In such situations, unnoticed contacts with blood probably account for most of the transmissions.

The immunisation programme against hepatitis B should not neglect other preventive measures. The main measures are: Always use condoms with casual sexual partners, do not exchange syringes or injection material, always apply universal precautions with blood and other biological liquids as these must always be considered potentially infectious.

Between 1988 and 1996, the Swiss Federal Office of Public Health received 200 to 500 reports of acute hepatitis B each year, mostly affecting adults aged 15 to 40 (80% of all reports). Considering the problem of underreporting and the fact that most infections are asymptomatic or remain undiagnosed because of atypical symptoms, the yearly incidence of new infections is estimated to be between 2000 and 3000. About 20,000 persons are chronically infected (0.3% of the population) and acute and chronic complications of hepatitis B (fulminant hepatitis, cirrhosis, hepatocarcinoma) lead to an estimated 40 to 80 deaths each year.

Since 1901, the Swiss Federal Office of Statistics has published at least each decade detailed mortality statistics from tuberculosis. These cross-sectional data on deaths from respiratory tuberculosis from 1901 to 1991 were utilized to analyse retrospectively tuberculosis death experience within each birth cohort. The cross-sectional data indicate that tuberculosis mortality increases with age in each successive decade. Nevertheless, the cohort-contour approach indicates that this phenomenon is the result of a much higher mortality that each cohort experienced in their early adulthood, and that mortality form respiratory tuberculosis in Switzerland always preferentially affected the young. The data also indicate that tuberculosis mortality in Switzerland has been decreasing for at least 160 years, and perhaps peaked as early as in the eighteenth century.

The Swiss Sentinel Network (SSN) has monitored influenza activity in Switzerland since 1986. Between 2600 and 6600 cases of influenza-like-illness (ILI) are reported each influenza season by the 150-200 general practitioners, internists and paediatricians who voluntarily participate in the SSN. Based on these figures, there are an estimated 100,000 to 230,000 cases of ILI in Switzerland each year during the main influenza-season (10 week-peak-periods). Among patients over 60 years, 13% to 20% developed pneumonia and 1.3% to 2.7% had to be hospitalised. This represents an estimated 1800 hospitalisations caused by influenza for the country as a whole each year. Based on data from the Swiss Medical Statistic VESKA (H+), there are an estimated 1600 hospitalisations per year, confirming the estimation of the SSN. Collaboration with the Swiss National Center for influenza allows identifications of circulating influenza-strains and the determination of eventual deviations from the vaccine strains. The SSN has been a valuable surveillance tool during the last ten years and has provided useful data on the extent and importance of influenza in Switzerland. It therefore makes an important contribution to the elaboration of targeted and appropriate prevention measures against influenza.

Two studies are presented. The first one concerns a mumps outbreak in a kindergarten in Geneva in June 1991. Of 26 children, nine (34.6%) got mumps. Of nine children vaccinated with the Rubini vaccine strain, seven had the disease as opposed to only one of 14 children vaccinated with the Urabe strain. The vaccine efficacy of the Rubini strain was estimated at 22% with a 95% confidence interval of -10% to 45%. The second study concerns a cluster of 112 mumps patients seen by a pediatrician in the Bernese Jura region between September 1992 and May 1993. A case-control study was carried out resulting in a vaccine efficacy estimate of 50% with a 95% confidence interval of -19% to 81%. Of the cases, 51 (45.5%) had been vaccinated against mumps, 50 of them (98%) with the Rubini vaccine strain. Of the controls, 30 (61.2%) had been vaccinated, 86.7% of them with Rubini. Methodological problems of case selection and their possible effects on the estimated vaccine efficacy are discussed. The results of these two studies have been confirmed by more recent investigations. In retrospect, we therefore conclude that small studies can serve as early indicators for epidemiological evidence and that they can be finally integrated into a more complete picture.

Unlabelled: Since 1990, there have been reports of an increasing number of mumps cases in Switzerland, in particular among vaccinated children, and of local outbreaks of mumps. Using data from the Sentinella reporting system, a network of voluntary participating doctors (general practitioners, internists and paediatricians, yearly average: n = 141), trends and factors influencing mumps incidence in the general population were assessed during the last seven years. Following an initial decline in mumps reports, since 1990, there has been a continuous and marked increase in reports from a minimum of 0.7 cases per physician and year in 1989/90 to a near five-fold increase of 3.3 cases in the last reporting period from June-December 1993 (calculated for one year). Half of this increase, which is reflected in a doubling of the number of cases reported in 1986/87, is explained by an increase in cases among vaccinated children. The trend in mumps cases contrasts with that of measles and rubella, where there has been a clear decline in these reports since 1986 (approximately 70-80%). Complications were reported in 75 (4.0%) of the total number of mumps patients (n = 1894); in 2/5 of the cases this was a meningitis, in 1/3 an orchitis. Based on available data on vaccination coverage, the estimated efficacy of the mumps vaccines against parotitis is between 47-77%; this is clearly lower than the corresponding figure for measles (91-97%) and rubella (89-97%) vaccines. The relatively low efficacy against parotitis is mainly due to a protective level of 13-73% of the vaccines containing the Rubini strain. The estimated efficacy of the Rubini vaccines against complications is 50-81%; it is nearly 60-90% if a possible reporting bias is taken into consideration., Conclusions: 1. The Rubini strain vaccines, which are the most commonly used in Switzerland, seem to have played an important role in the clear increase in mumps cases since 1990. 2. The situation seems more favourable concerning the efficacy against complications of the vaccines used. 3. Our data support the high efficacy of all measles and rubella vaccines. 4. The surveillance of MMR by the Sentinella reporting system provides a useful and effective manner to evaluate the MMR vaccination programme.