Objective: Description of measles epidemic in the Netherlands, 1999-2000.
Design: Observational descriptive study.
Methods: Intensified surveillance of measles cases by means of a case register established at the 'Landelijke Coördinatiestructuur Infectieziektebestrijding (LCI)' [National Co-ordination Centre for Communicable Disease Outbreak Management].
Results: There were 3,292 reported measles patients, most of whom came from areas with low vaccine coverage. Of these patients, 94% had not been vaccinated; in 85% of cases this was for religious reasons. Of the 158 (5%) vaccinated patients, 157 had not (yet) received a second dose of vaccine. The incidence of measles increased with decreasing vaccine coverage in a municipality, both for unvaccinated and vaccinated persons. Three of the reported patients died. The percentage of patients with one or more complications was 22% in the group < 15 months of age, 19% in the group 15 months-4 years, 16% in the group 5-9 years, 11% in the group 10-19 years, and 15% in the group > 19 years of age.
Conclusion: Considering the complications observed, the epidemic described involved a serious disease. Vaccination was accompanied by effective protection against measles infection and its complications. Herd immunity outside the unvaccinated groups was sufficient to prevent an epidemic there. However, incidental spread to vaccinated children did occur; the greatest risk factor for acquiring measles for vaccinated children is a stay in an area with low vaccine coverage.