Enhanced surveillance of primary measles mumps and rubella (MMR) immunisation in Wales.

In England and Wales routinely available data measure uptake of the measles mumps and rubella (MMR) vaccine at 2 years. This results in a delay in detecting change in uptake of the vaccine, which is scheduled at 12 months of age. The predictive value of uptake at 15-17 months is limited by the greater variability in uptake between quarters at the younger age. This can be overcome by presenting the data as a four-quarter annual rolling average. Uptake of the MMR vaccine at 2 years of age in Wales is predicted to stabilise at around 84% in the first three quarters of 2002.