change of study design

Hospital-Acquired Influenza (HAI) is closely linked to the intensity of influenza in the community. HAI is associated with significant morbidity, mortality and extra costs due to prolonged hospital stay. The incidence of laboratory confirmed HAI has been reported rarely. The proportion of HAI among influenza cases was 11.38% (95% Confidence Interval: 5.19%-19.55%) in a meta-analysis of 14 studies. In France, a prospective surveillance study of adults with Influenza-Like Illness (ILI) over 11 years, reported that 35.6% of the influenza cases diagnosed at hospital were hospital-acquired.

HAI is transmitted via respiratory droplets and by hand contacts. The spread is facilitated by Health Care Professionals (HCPs), patients and visitors.

Prevention and control of HAI is of upmost importance to preserve patient safety and limit the related economic costs. While vaccination of HCPs has been shown to contribute to the reduction of HAI, less is known on the impact of patient vaccination on the risk of HAI during hospitalization.

The aim of this study is to describe the hospital-acquired influenza in a french university hospital.

Inclusion Criteria:

• Any volunteer adult patient (≥ 18 years of age) hospitalized for at least 24 hours on a study unit, who had a nasopharyngeal swab taken as part of care for the purpose of diagnosing influenza by PCR testing and who had an influenza-like illness meeting the following definition:
• Fever greater than 37.8°C in the absence of antipyretics; And/or
• Cough or pharyngeal pain.

Exclusion Criteria:

• Any person who does not meet the above definition or who has expressed opposition.

Any volunteer adult patient (≥ 18 years of age) hospitalized at Edouard Herriot Hospital for at least 24 hours on a study unit, who had a nasopharyngeal swab taken as part of care for the purpose of diagnosing influenza by PCR testing and who had an influenza-like illness meeting the following definition