[Analysis of evolution of vaccine coverage in Niakhar, a rural area of Senegal, between 1984 and 2003].

In Senegal, the Expanded Programme of Immunization started by 1986 as a routine programme targeting 7 diseases: tuberculosis, tetanus, diphtheria, pertussis, poliomyelitis, measles and recently yellow fever Immunization against hepatitis B and Haemophilus influenzae b are proposed since 2005, but not implemented yet. In addition, there are mass immunization campaigns, such as National Immunization Day organized every year since 1999 against poliomyelitis and, in case of outbreak, against meningitis or yellow fever. In a 30,000 inhabitants rural study zone, vaccine contacts of children under 15 years of age are updated regularly several times a year since 1984. We also performed yearly cross sectional surveys from 1999 to estimate vaccine coverage in children of 24 months of age. Immunization status was assessed by vaccination cards presented by the children's parents and registers of health centres. We compared the results from both longitudinal and cross sectional surveys, which showed some differences. The last method seemed to indicate higher immunization rates. The vaccine coverage was slightly but not significantly higher in the study zone compared to the general vaccine coverage in Senegal, excepted for measles immunization for which the coverage was significantly lower in Niakhar. However results showed that interventions of all types lead to a high vaccine coverage (up to 80%) but are not sustainable. In the intervals, vaccine coverage decreased dramatically (below 40%), due mainly to irregular supply of antigens and poor accessibility of health facilities. Other factors are mentioned.