Most Early Cases of H1N1 Across China Were Mild

Research into May and June cases highlights rapid improvements in surveillance in China

WEDNESDAY, Dec. 9 (HealthDay News) -- Most cases of H1N1 influenza seen in China during the early summer were mild, and initiating oseltamivir within 48 hours of symptom onset could reduce the duration of viral shedding, according to research published online Dec. 9 in the New England Journal of Medicine.

Bin Cao, M.D., of the Capital Medical University in Beijing, and colleagues reviewed characteristics of the first 426 patients hospitalized in China in May and June with confirmed cases of H1N1 infection. Roughly one-third of cases were identified at ports of entry to China, where thermal scanners were installed and millions of travelers were screened during the summer.

The researchers found that the most common symptoms in patients were fever and cough (in 67.4 and 69.5 percent, respectively). Many patients had lymphopenia (68.1 percent of adults and 92.3 percent of children). Fever generally lasted for two days, and patients had positive real-time reverse-transcriptase-polymerase-chain-reaction test results for a median of six days. Factors associated with prolonged viral infection included being younger than 14 years and having more than 48 hours delay between symptom onset and oseltamivir treatment.

"The report by Cao and colleagues demonstrates the progress China has made in developing robust surveillance in a relatively short period. Surveillance has also improved in the United States, where detection of the first two cases of H1N1 infection was the result of investments leading to experimental diagnostic tests and enhanced border surveillance," writes the author of an accompanying editorial.

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