Risk Factors and Vaccine Failure Associated With Influenza Related Death in Severe Cases in Greece During the 2014-15 Season

Abstract

Background We examined risk factors for influenza related death in all severe cases in Greece during the 2014-15 influenza season. Methods A national severe influenza surveillance network includes reporting to the Hellenic Ctr for Disease Control & Prevention (HCDCP) of all laboratory-confirmed influenza cases admitted to ICU &/or in-hospital deaths of influenza patients. Each case is followed up daily, with a structured questionnaire until discharged. We evaluated risk factors for death using univariate & multivariate analyses. Results 248 cases were recorded (median age 67 yrs, 54.7% male, 87.1% high risk pts with comorbidities). Influenza A was noted in 56.5%. 111 deaths were recorded (median age 57 yrs, 55% male). In 64 (57.7%) deaths, influenza A was diagnosed [A(H1N1): 36%, A(H3N2): 64%]. 99/111 (89.2%) deaths occurred in pts with immunization indications; 15 were immunized. ARDS (OR 3.43 (95%CI 1.27 9.3) p=0.006), renal insufficiency (OR 3.9; 95% CI 1.4-11.3, p = 0.01), occurrence of secondary bacterial infection & septic shock (OR 4.4; 95% CI 1.2-16.4, p=0.015) were risk factors for death. Influenza A cases did not differ from B regarding age, comorbidities, rates of intubation or death. Within 31 vaccinated cases influenza A was more prevalent to B (77.4% vs. 22.6%, p=0.06). Conclusion ARDS, renal insufficiency & the presence of secondary infections or septic shock were risk factors for death in a mixed A & B season. Influenza B did not differ from A in the risk for complications & death. Vaccine failures were noted especially among serious influenza A cases, consistent with the reported drift of A(H3N2). Sotirios Tsiodras, MD, DSc University of Athens Med. Sch. Athens, Greece 1 Rimini Street 12462 Athens, Greece Tel: 0030 210 58 31 641 Tel (2nd): 0030 693 26 65 820 FAX: 0030 210 53 26 446 e-mail: tsiodras@med.uoa.gr