Repeat vaccinations key to measles control.

Repeated mass vaccination campaigns are needed to reduce measles deaths and illness in Africa, but barriers are making it difficult to carry out such campaigns, according to a February study in the Lancet.

Because measles is such a widespread public health problem in Africa, the World Health Assembly set a five-year goal in 2005 to reduce measles mortality by 90 percent from 2000 levels. The study's authors said that goal is achievable "but will need sustained resources and efforts, and further reductions in measles mortality face several obstacles."

Those obstacles include difficulties in maintaining high levels of routine measles vaccination coverage, high HIV prevalence and potential clustering of infected people, particularly in densely populated urban areas. The study, published online Feb. 10 in the Lancet, is based on a cross-sectional survey in Lusaka, Zambia, and found that among 1,000 children, 84 percent had a history of measles vaccination but only 67 percent had antibodies to measles virus.

"One of the challenges to continued progress in reducing measles incidence and mortality is the need for repeated mass measles vaccination campaigns," the study's authors wrote. "These campaigns require the sustained commitment of resources and personnel, are typically done within 3 years to 4 years of the initial campaign and target a narrower age group than initial catch-up campaigns."

They suggested that cross-sectional surveys, using oral fluid specimens and satellite images for sampling could be useful in identifying the optimal timing of repeat vaccination campaigns "before large outbreaks of measles occur."

For more, visit www. thelancet.com.