Reported rates of MMR vaccine uptake in London at 2 years of age fell from the mid-1990s to 73% in late 2001 compared to 84% for England as a whole.¹ Nationally, coverage decreased by a greater proportion in affluent compared to deprived areas.² Mathematical modelling has predicted this drop would be sufficient to sustain measles transmission in nine health authorities in England and Wales, seven of them in London.³ However, substantial measles outbreaks remained rare in London from 1996 to mid-2001, occurring primarily as small clusters in religious and other communities opposed to vaccination. The largest outbreak consisted of 43 confirmed cases in east London in early 2001.⁴

In late December 2001 a cluster of confirmed measles cases was reported among preschool children in south London, the start of the …