Influenza outbreak - how best to prevent beyond vaccination?

Abstract

Background: Influenza vaccination, is the cornerstone of influenza epidemics prophylaxis, but there is some evidence of its lower efficacy in the elderly and in some other high-risk groups of the population.Aims and Methods: We analysed the demographic characteristics of the patients (pts) hospitalized in an internal medicine ward (IMw) during the 2016-17 flu season, investigating whether there had been previous prevention, and overall how the infection progressed. All pts admitted to our hospital center, with positive nasopharyngeal swab, from the 1st October 2016 to the 28th February 2017 were recorded (n = 221), from which the inpatient IMw subgroup (31 pts) was selected.Summary of results: Of the 31 selected IMw pts, 61.3% were female and 38.7% male. Their chronic main medical condition included diabetes mellitus type 2 (32.3%) and heart failure (22.6%). Although more than half was previously vaccinated with that year’s vaccine (65.5%), all pts required hospitalization, with a high average length of stay (11.3 ± 5.2 days). H3N2 was the predominant subtype (90.3%). Flu symptoms at admission were present in 80.6% of the pts, and their mean PaO2/FiO2 ratio was 288.9 ± 40.7. We observed an increased in infection severity in patients with asthma, obesity and chronic kidney disease (when compared to controls) with PaO2/FiO2 ratio 284.0 ± 58.7, 95%CI 229.9-338.6, PaO2/FiO2 ratio 242.5 ± 12.0; 95%CI 134.5-350.5 and PaO2/FiO2 ratio 263.0 ± 33.9; 95%CI -41.9-567.9 respectively. No transfers were needed to intensive care, and one only patient required non-invasive mechanical ventilation.Conclusions: During a flu epidemic, there is a constant need for health staff to perform the influenza test in all seeking care pts with respiratory / generalized pains complaints. Preventive use of oseltamivir by the most vulnerable contacts exposed to the virus, even if previously vaccinated, appears to be justifiable.