Monday, 2 December 2013

North and South China need separate flu vaccination schedules

by Michael Woodhead
Climatic variation precludes a single national influenza schedule for China, and instead there should be two separate programs for northern and southern areas of the nation, say infectious disease experts.
Dr Yu Hongjie and co-researchers from the Key Laboratory of Surveillance and Early-warning on Infectious Disease, Chinese Centre for Disease Control and Prevention, Beijing, have found that China has two distinct patterns of influenza in northern and southern regions.
In a study of influenza reports from 30 provinces between 2005 and 2011 they found that influenza A levels were much more prominent and seasonal in the north compared to the south of China. Epidemics peaked in January–February in northern China and April–June in southernmost regions. Provinces in central China showed semi-annual influenza A patterns with peaks in January–February and June–August. With influenza B, infections predominated in colder months throughout most of China. The researchers said their findings showed that regional-specific influenza vaccination strategies would be best for China;
“These findings show that influenza seasonality in China varies between regions and between influenza virus types and suggest that, as in other settings, some of these variations might be associated with specific climatic factors."
“Overall, these findings suggest that, to optimize routine influenza vaccination in China, it will be necessary to stagger the timing of vaccination over three broad geographical regions … Annual campaigns should be initiated 4–6 months apart in Northern and Southern China."
Full study: PLOS Medicine

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