Saturday, 10 May 2014
Measles resurgent in China as migrant children miss vaccinations
China looked like it was on track to eliminate measles until two years ago, but now the infection is making a comeback among unvaccinated young children, the World Health Organisation has warned.
In a report of the progress towards measles elimination in China a WHO surveillance study notes that China has seen dramatic reductions in rates of measles since it implemented and expanded childhood vaccination campaigns in the 1980s and 1990s. Rates of the infection fell from 572 per 100,000 in the 1960s to below 10 per 100,000 since the 1990s. Since then, further reductions in measles have been seen as children have been given two doses of measles vaccine with uptake rates of more than 90%. There have also been additional 'catch up' measles vaccination campaigns in provinces where continuing outbreaks of measles have occurred. This resulted in the annual number of cases coming down from 140,000 per year in 2008 to under 10,000 in 2012. However, as the WHO Bulletin report notes, there has been a resurgence in 2013, with the number of cases bouncing back to around 24,000 in that year. The report says most of the measles cases occurred in young children who had missed one or all of their scheduled vaccination doses, although a few also occurred in adults. It says the resurgence is disappointing, especially as it follows intensive 'catch up' campaigns. In their report, the WHO researchers say it is likely that many of the unvaccinated children spreading measles will belong to migrant worker families who have left their hometown and thus drop out of the measles vaccination and reporting programs based in schools and local health centres.
"The resurgence of measles seen among young unvaccinated Chinese children in 2013 indicates a weakness in routine immunisation that allows some children to miss one or both of their scheduled doses of measles vaccine. Such weakness must be eliminated if a further resurgence in the next few years is to be avoided and measles is ever to be eliminated in China," they conclude.
"Improvements in the identification and location of children who are new to an area may permit marked improvements in vaccine coverage" they note.