Academic journal article Bulletin of the World Health Organization

Measles: Effect of a Two-Dose Vaccination Programme in Catalonia, Spain

Academic journal article Bulletin of the World Health Organization

Measles: Effect of a Two-Dose Vaccination Programme in Catalonia, Spain

Article excerpt

Voir page 136 le resume en francais. En la pagina 136 figura un resumen en espanol.

Introduction

Throughout history, measles has occasioned high mortality and morbidity. Nowadays, despite being a preventable disease, it still gives rise to 45 million cases and over one million deaths worldwide each year (1, 2).

The availability of an attenuated vaccine of proven high efficacy (90-95%), the markedly stable nature of the virus, the nonexistence of carriers, and the fact that humans constitute the sole disease reservoir (3, 4), led to the proposal that measles could be eliminated from extensive geographical areas. Hence, within the context of the strategy of "Health for all by the year 2000", the European Region of WHO proposed that measles should be eliminated from all countries in the region by the year 2000.

Subsequently, however, epidemiological data have indicated that in developed countries, even with vaccine coverage approaching 100%, sporadic cases and epidemic outbreaks of measles could continue to appear (5, 6), owing to the difficulty of achieving sufficient herd immunity to eliminate a disease whose level of airborne communicability is far higher than had been supposed. In 1991 the European Region of WHO therefore set a new target: that by the year 2000 the incidence of measles in all Member States in the region would be less than 1 per 100 000 inhabitants. More recently it has been recommended that the date for elimination should be set between 2005 and 2010 (7). Diverse strategies have been proposed to control the disease and its subsequent eradication (3, 4, 8). It is absolutely essential, however, that region-specific measles epidemiology should be ascertained so that the methods best adapted to the respective characteristics of each location can be applied (9, 10).

In Catalonia (population 6 million), an autonomous region situated in north-east Spain, a systematic immunization programme was introduced in 1981, based on the administration of a single dose of measles vaccine at the age of 12 months. Since 1988, two doses of vaccines have been administered: the first at 15 months, and the second at 11 years. On the basis of the number of doses of vaccine distributed to vaccination centres, it is estimated that vaccination coverage for cohorts born after 1981 is in excess of 95%. In 1991 a health plan was drawn up which aimed among other things at eliminating indigenous measles by the year 2000 and reducing the disease incidence to less than 10 per 100 000 by 1995. Nevertheless, and bearing in mind that surveillance was incomplete, the lowest incidence for the entire period (10.6 per 100 000 inhabitants) occurred in 1993, with no epidemic outbreak of measles being detected. In 1994 and especially in 1995 there was a rise in the incidence and the number of reported outbreaks.

The present study sought to assess the measles elimination strategy in Catalonia by examining incidence trends over the last 25 years and analysing the specific characteristics of the outbreaks registered in the period 1986-95.

Materials and methods

Historically, records of notifiable diseases in Spain have been based on the number of cases reported by local public health authorities. In January 1982, a directive came into force in Catalonia which reformed the disease notification procedure. Under the terms of this directive, in addition to local public health authorities, the heads of health care centres (in- and outpatient) were also required to return a form showing the number of diseases diagnosed by all physicians in their centres. Among the diseases to be reported by this procedure was measles, which, along with the others, was to be reported on a clinically suspect case basis, as determined by the physician's criteria.

It was subsequently recommended that the following clinical case definition of measles be used for reporting purposes: a disease displaying the following characteristics: a) generalized maculopapular rash; b) fever [is greater than] 38. …

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