Evaluation of a mass measles immunisation campaign in a rapidly growing peri-urban area.

A mass measles immunisation campaign, with a target coverage rate of 85-90%, was launched in Khayelitsha, a rapidly growing urban township in the Cape Town area. Cross-sectional surveys of the measles immunisation status of resident 6-23-month-old infants were conducted immediately before, immediately after, and approximately 2 months after the campaign in order to determine the effectiveness of a mass campaign in boosting coverage in an area with a high influx rate. Immunisation coverage rates were 55% in the first survey, 76% in the second, and 72% in the third. In the first survey, coverage rates for children born in Cape Town were 1.4 times higher than those born elsewhere. This trend continued throughout the survey. Duration of stay in Cape Town also influenced coverage, with rates for the recently arrived children being considerably lower than those for the more established Cape Town residents. The influx rate between the second and third survey (over the Christmas period) was 9.1% per month. Failure to reach the targeted rate is attributed to the influx rate, campaign design and implementation, and factors related to child and career mobility. Alternative immunisation strategies, with social awareness playing a key role, are being urgently investigated.