In a study conducted by a research team of Chinese and American scientists, researchers found that while flu season in northern China occurs during the same period as the world's other northern temperate zones, the flu season in the south peaks in the spring. The team said a third intermediate flu zone contains complex patterns that require more research.
Researchers with the National Institutes of Health's Fogarty International Center collaborated with the Chinese Centers for Disease Control and Prevention on the study, which was part of the Multinational Influenza Seasonal Mortality Study.
"This research suggests the need for staggered timing of vaccination in three broad epidemiological regions," Cecile Viboud, the co-author of the study, said.
The researchers recommend that northern China conduct its annual vaccination campaign in October, while southern China should start its campaign in February. The study authors said the mid-latitude provinces around Shanghai would require more research to determine the optimal vaccination policy.
"Before a national influenza vaccination program can be established in this large, climatologically diverse country, public health experts need a clear picture of influenza seasonally across the country that could be used to optimize the timing of a future Chinese vaccination effort," Viboud said.
China introduced the seasonal flu vaccine in 1998, but the country reports that only around two percent of the population is routinely immunized. An estimated 11 to 18 flu deaths occur per 100,000 people in China annually.