Epidemiological and clinical features of 308 hospitalized patients with novel 2009 influenza A (H1N1) virus infection in China during the first pandemic wave.

OBJECTIVES

To investigate the epidemiological and clinical features of 308 hospitalized patients suffering from infection with novel H1N1 influenza virus in China from May to August 2009, and to examine the effects of oseltamivir treatment for mild cases.

METHODS

Information on H1N1 influenza patients confirmed by real-time RT-PCR assay was gathered and analyzed from an influenza surveillance system, including demographic features, clinical symptoms and signs, therapeutic regimen, and duration of fever and virus shedding.

RESULTS

The clinical course of infected individuals appeared mild. Mainly young adults were affected. Most cases had low or mid-level fever, cough, headache, rhinorrhoea, and sore throat. Few patients had vomiting (1.3%) and diarrhea (3.9%). Oseltamivir treatment did not shorten the duration of fever. Furthermore, early oseltamivir treatment as well as early conventional supportive treatment without antiviral drugs contributed to a reduction in the duration of virus shedding.

CONCLUSIONS

In the first pandemic wave, novel H1N1 virus caused disease primarily in adults, causing mild febrile illness. Mildly ill patients cleared the virus rapidly even in the absence of oseltamivir treatment.