title: Clinical differences between H3N2 and H1N1 influenza 2012 and lower respiratory tract infection found using a statistical classification approach.
abstract: BACKGROUND
  Influenza A H1N1 and H3N2 are two influenza waves that have been identified in past years.
  
  
  METHODS
  Data from 77 inpatients from three tertiary hospitals were included and statistical analysis was performed in three different clusters.
  
  
  RESULTS
  Thirty-four patients (44.2%) had respiratory distress upon admission, 31.2% had a smoking history or were active smokers, 37.7% manifested disease symptoms, and 7.8% were obese (body mass index >41). The mean age of patients was 51.1 years. Cough was the most common symptom observed in 77.9% of the patients, accompanied by sputum production (51.9%) and fatigue (42.9%). Hemoptysis and vomiting were rarely recorded in the patients (9.1% and 16.9%, respectively). Oseltamivir administration varied between 0 and 10 days, giving a mean value of 2.2 days. In particular, 19 patients received no drug, 31 patients received drug for only for 1 day, 19 patients for 5 days, and 8 patients from 2 to 10 days.
  
  
  CONCLUSIONS
  Clusters of symptoms can be used to identify different types of influenza and disease severity. Patients with vaccination had pneumonia, whereas patients without vaccination had influenza A. Patients more than 54.5 years old had H3N2 and patients less than 54.5 years had H1N1. White blood cell count values increased from normal to elevated in H3N2 patients but still remained abnormal in lower tract infection and H1N1 patients.
authors.affiliation: Department of Food Technology, Alexander Technological Educational Institute of Thessaloniki, Thessaloniki, Greece.
authors.forename: Dimitris
authors.initials: D
authors.lastname: Petridis
authors.affiliation: Pulmonary Department, "G Papanikolaou" General Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece ; Department of Interventional Pneumology, Ruhrlandklinik, West German Lung Center, University Hospital, University Duisburg-Essen, Essen, Germany.
authors.forename: Paul
authors.initials: P
authors.lastname: Zarogoulidis
authors.affiliation: 2nd Pulmonary Department, "Sotiria" Hospital for Chest Diseases, Athens, Greece.
authors.forename: Anastasios
authors.initials: A
authors.lastname: Kallianos
authors.affiliation: Pulmonary Department, "G Papanikolaou" General Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece.
authors.forename: Ioannis
authors.initials: I
authors.lastname: Kioumis
authors.affiliation: Department of Clinical Therapeutics, Division of Pneumonology, Medical School, National University of Athens, Athens, Greece.
authors.forename: Georgia
authors.initials: G
authors.lastname: Trakada
authors.affiliation: Pulmonary Department, "G Papanikolaou" General Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece.
authors.forename: Dionysios
authors.initials: D
authors.lastname: Spyratos
authors.affiliation: Pulmonary Department, "G Papanikolaou" General Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece.
authors.forename: Antonis
authors.initials: A
authors.lastname: Papaiwannou
authors.affiliation: Pulmonary Department, "G Papanikolaou" General Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece.
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Porpodis
authors.affiliation: Department of Respiratory Diseases, Changhai Hospital/First Affiliated Hospital of the Second Military Medical University, Shanghai, People's Republic of China.
authors.forename: Haidong
authors.initials: H
authors.lastname: Huang
authors.affiliation: 2nd Pulmonary Department, "Sotiria" Hospital for Chest Diseases, Athens, Greece.
authors.forename: Aggeliki
authors.initials: A
authors.lastname: Rapti
authors.affiliation: II Medical Department, "Coburg" Regional Clinic, University of Wüerzburg, Coburg, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Hohenforst-Schmidt
authors.affiliation: Pulmonary Department, "G Papanikolaou" General Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece.
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Zarogoulidis
keywords: H1N1; H3N2; influenza outbreak; respiratory infection; vaccination