Objective: To determined the viral shedding of the young adult patients with mild 2009 H1N1 influenza in China to provide data for better nosocomial infection measures.
Methods: From Sep 2009 to Jan 2010, the clinical data and serial nasopharyngeal swabs of 67 patients with 2009 H1N1 influenza and 37 patients with seasonal influenza aged from 18 to 35 years old were collected. The nasopharyngeal swab samples were detected by Real Time RT-PCR to determine the viral shedding. All the patients were not given antiviral therapy but Chinese medicine for detoxicating.
Results: For the H1N1 patients, the median interval between the symptom onset and the undetectable RNA was six days (4 ~10d). But viral shedding was still found in 31.3% patients after 7 days following illness onset. The median interval between disappearance of fever and an undetectable viral RNA level was three days (2~8d), and 17.9% patients were found to be viral shedding 6 days later after normalization of body temperature. For the seasonal influenza patients, 94.6% patients were detected out viral RNA within 7 days. The median interval of seasonal influenza between the symptom onset and the undetectable RNA was four days ( 3-8d). The median interval between disappearance of fever and an undetectable viral RNA level was three days (2~6d).
Conclusion: It suggests that 7 days isolation period from the illness onset or 24 hours after the resolution of fever and respiratory symptoms are not long enough to cut off the transmission among Chinese young adults with mild illness.