Objective: To describe the initial effects of the large-scale vaccination campaign in June-July of 2002 (1-5- and 15-18-year-olds) and September-November of 2002 (6-14-year-olds) on the incidence of group-C meningococcal disease in the Netherlands.
Design: Descriptive.
Method: The incidence of meningococcal disease and the serogroup distribution were determined on the basis of the patient data associated with isolates of Neisseria meningitidis that were sent to the Netherlands Reference Laboratory for Bacterial Meningitis during the period from 1 January 1999 to 31 January 2003.
Results: The highest monthly incidence of serogroup-C disease was reported in January-April 2002 (2.2-3.1/100,000), after which the incidence remained more or less unchanged after September at a level of 0.1-0.4/100,000. The incidence of meningococcal-C disease was 73% lower in August-October 2002 compared with the same period in 2001. In the same months, the incidence of meningococcal-C disease for the 0, 1-5, 6-14, 15-18 and > 18 year-olds was 49%, 80%, 89%, 89% and 42%, respectively, lower than in the same months in the previous year. The percentage of meningococcal disease caused by serogroup-C fluctuated from 35 to 49% in January-August 2002 and decreased to 9-19% in September-December 2002. There was also a decrease in the unvaccinated age groups.
Conclusion: The vaccination campaign led almost immediately to a sharp decrease in the number of patients with meningococcal serogroup-C disease.