BACKGROUND: Since 1995, measles vaccination at nine and 18 months has been routine in South Africa; however, coverage
seldom reached .95%. We describe the epidemiology of laboratory-confirmed measles case-patients and assess the impact
of the nationwide mass vaccination campaign during the 2009 to 2011 measles outbreak in South Africa.
METHODS: Serum specimens collected from patients with suspected-measles were tested for measles-specific IgM antibodies
using an enzyme-linked immunosorbent assay and genotypes of a subset were determined. To estimate the impact of the
nationwide mass vaccination campaign, we compared incidence in the seven months pre- (1 September 2009–11 April
2010) and seven months post-vaccination campaign (24 May 2010–31 December 2010) periods in seven provinces of South
RESULTS: A total of 18,431 laboratory-confirmed measles case-patients were reported from all nine provinces of South Africa
(cumulative incidence 37 per 100,000 population). The highest cumulative incidence per 100,000 population was in children
aged ,1 year (603), distributed as follows: ,6 months (302/100,000), 6 to 8 months (1083/100,000) and 9 to 11 months
(724/100,000). Forty eight percent of case-patients were $5 years (cumulative incidence 54/100,000). Cumulative incidence
decreased with increasing age to 2/100,000 in persons $40 years. A single strain of measles virus (genotype B3) circulated
throughout the outbreak. Prior to the vaccination campaign, cumulative incidence in the targeted vs. non-targeted age
group was 5.9-fold higher, decreasing to 1.7 fold following the campaign (P,0.001) and an estimated 1,380 laboratoryconfirmed
measles case-patients were prevented.
CONCLUSION: We observed a reduction in measles incidence following the nationwide mass vaccination campaign even
though it was conducted approximately one year after the outbreak started. A booster dose at school entry may be of value
given the high incidence in persons .5 years.