Vaccination--coverage of under-fives, validity of records, and the impact of mass campaigns in the Edendale/Vulindlela district of KwaZulu.

Recent epidemics of poliomyelitis and measles in the Edendale/Vulindlela district of KwaZulu spurred an investigation into the causes of vaccination failure. Vaccination coverage achieved by routine clinic services and by two mass campaigns was assessed. The validity of routine clinic vaccination records was also determined. Using a modified 30 x 7 random cluster sampling technique, 224 children aged 1-5 years were studied. Of these, 62% had a 'Road to Health' card. Best estimates show that 87% had had BCG, 62% three doses of diphtheria, pertussis and tetanus and polio, and 55% measles vaccine. The mass campaigns raised coverage for measles by 26%, and that for polio by 27%. Coverage estimates made from routine clinic data were consistently 13-25% higher than from this survey. This discrepancy is unfortunate, since it could lead to complacency if certain targets are apparently achieved using only clinic records, and points to the need for regular population-based surveys in all but the best organised health services. Inadequate vaccination coverage alone can explain the epidemics of polio and measles. The reasons for this, in the presence of an adequate clinic infrastructure, need to be assessed urgently to prevent further outbreaks.