Comparisons of Clinical Characteristics between Adult Patients with 2009 H1N1 Influenza and Those with Seasonal Influenza during the 2009 Epidemic in Thailand

Abstract

SUMMARY:Clinical presentations of patients with 2009 H1N1 influenza are generally similar to those of patients with seasonal influenza. A cross-sectional study was conducted among adults at an outpatient clinic in a university hospital setting during the 2009 epidemic. Infections in all patients were confirmed by real-time reverse transcription-polymerase chain reaction. There were 269 patients with 2009 H1N1 influenza and 128 patients with seasonal influenza. Compared with patients with seasonal influenza, patients with 2009 H1N1 influenza were more likely to be aged º20 years (25.7z vs. 8.6z, P º 0.001) and to be students (38.7z vs. 22.0z, P ＝ 0.001), or healthcare workers (20.1z vs. 10.9z, P ＝ 0.022); however, they were less likely to have an underlying disease (25.6z vs. 39.8z, P ＝ 0.004) and influenza vaccination (4.2z vs. 12.2z, P ＝ 0.021). There were no differences in the illness duration, vital signs, and symptoms between groups. Patients with seasonal influenza were more likely to be admitted to the intensive care unit (2.4z vs. 0z, P ＝ 0.033) and exhibited a higher mortality rate (2.4 z vs. 0z, P ＝ 0.093). A history of contact with a confirmed 2009 H1N1 influenza case (odds ratio [OR] ＝ 12.91, P º 0.001) and age (OR ＝ 1.05 per 10 years younger, P ＝ 0.015) were associated with 2009 H1N1 influenza infections. In conclusion, these results showed differences in characteristics between the patients with 2009 H1N1 influenza and those with seasonal influenza.

Novel Avian-Origin Influenza A (H7N9) in Critically Ill Patients in China*

“…Conjunctivitis, a common finding with H7 human infections (15), was also not reported among the patients in our study. Diarrhea or vomiting was reported in 7.6% of patients in our study, which was similar to patients with season influenza infection (14).…”

Impact of influenza in the post‐pandemic phase: Clinical features in hospitalized patients with influenza A (H1N1) pdm09 and H3N2 viruses, during 2013 in Santa Fe, Argentina

“…Influenza shows a broad clinical spectrum, from mild illness to severe respiratory infection, developing bronchitis, pneumonia and complications such as respiratory failure, and multiple‐organ damage . It is important to characterize the clinical and epidemiological pattern of the influenza H1N1pdm virus and compare it with seasonal influenza, as surveyed in just a few studies in the post‐pandemic phase, in order to contribute to the implementation and strengthening of influenza control and prevention strategies.…”

Clinical Characteristics Are Similar across Type A and B Influenza Virus Infections

“…Far less reports are available on clinical manifestations by influenza type and subtype among adults. Medically-attended influenza A(H3N2) patients were found to be more severely ill than patients infected with other virus (sub)-types [ 14 – 15 ]; influenza B patients presented more frequently with gastrointestinal symptoms [ 14 ]; and few or no differences were observed in the clinical presentation of out- and in-patients with pandemic vs. seasonal A(H1N1) influenza [ 16 – 17 ]. However, no consistent differences were observed in the clinical presentation of outpatient-attended influenza patients by virus type [ 18 – 19 ], except for fewer signs and symptoms among patients with pandemic A(H1N1) vs. A(H3N2) or type B virus infection.…”