Effect of Influenza Vaccination of Healthcare Workers (HCW) on the Risk of Influenza in Patients Hospitalized in Short Stays Units

Influenza Vaccination of HCW and Hospital Acquired Influenza in Patients

Hospital acquired influenza is associated with significant morbidity and mortality in hospitalized patients notably elderly patients. Vaccination of HCW is recommended to prevent influenza transmission in healthcare setting.

Outbreaks of hospital acquired influenza were reported in stays with high vaccine coverage in patients (higher than 85%). It is necessary to underline that an adequate vaccine cover in the elderly population will not necessarily result in a total control of the incidence. Consequently, the prevention of influenza outbreaks in this vulnerable population must also include the reduction of the exposure to the influenza viruses, in particular thanks to the vaccination of HCW.

A pilote case-control study, implemented in Edouard Herriot hospital (at Lyon University hospitals), indicates that a shielding effect of more than 35% of vaccinated HCW on hospital acquired influenza among patients (Bénet et al.; BMC Infectious Diseases 2012). The results suggest a protective effect but investigations, carried out on a more important sample are needed to validate the benefit of HCW vaccination.

The aim of this prospective multicentric cohort study is to estimate incidence of influenza among hospitalized patients according to % of influenza vaccination of HCW in short stay units.

Inclusion Criteria:

• All adults patients and healthcare workers of the participating units
• With Influenza Like Illness

Exclusion Criteria:

• Patients aged < 18 years