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Influenza vaccination plan recommended for China
Chinese and American researchers are recommending that China tailor its influenza vaccination strategies based upon local disease patterns.
Their study findings, published in PLoS Medicine, indicate the need to stagger the timing of vaccination across three epidemiological regions in the country.
Cécile Viboud, PhD, a staff scientist with the Fogarty International Center at the NIH, and colleagues from Fogarty and the Chinese CDC compiled weekly reports of laboratory-confirmed cases of influenza A and influenza B infections from hospitals in 30 Chinese provinces from 2005 to 2011. They used linear regression analyses to estimate the seasonal characteristics of influenza, including the peak timing of each influenza season.
Cécile Viboud
On average, influenza A epidemics peaked during winter months in the northern provinces of China, between late December and early January, whereas provinces at intermediate latitudes experienced semiannual influenza A seasons, peaking between January and February and again between June and August. In the south, influenza A epidemics tended to peak once between mid-May and mid-June.
The researchers found less geographic variation in the seasonality of influenza B, which tended to peak throughout most of China during winter months.
Based on their findings, Viboud and colleagues recommend that northern China conduct vaccination campaigns starting in October — which is typically recommended for the Northern Hemisphere — and that the southernmost provinces should launch their campaigns in February. Because seasonal influenza activity in the mid-latitude region is more complex, peaking twice a year, the researchers said more data are needed before a recommendation can be made for that region.
"Optimizing the timing of influenza vaccination is particularly tricky in tropical locations where influenza circulates year-round or twice a year," Viboud told Infectious Disease News. "Routine influenza immunization involves a delicate balance between vaccinating early enough in the season so that protective antibodies have time to rise before the onset of the epidemic, but not so early that antibodies have waned by the time influenza arrives. The optimal timing of annual immunization remains unclear in regions that experience two peaks of influenza activity within the year, such as the region around Shanghai, China." — John Schoen
Cécile Viboud, PhD, can be reached at viboudc@mail.nih.gov.
Disclosure: The researchers report no relevant financial disclosures.