In December 2019, a new pandemic emerged, the COVID-19 disease caused by a SARS-Cov-2 virus. One of the most common symptoms of COVID-19 is mainly respiratory failure and patients requires assistance by mechanical ventilation. Ventilator-associated pneumonia (VAP) is a risk of this assistance. Since the beginning of the pandemic, Standard of care have evolved with new data. The prevalence of these VAPs seems significantly higher in the population of patients with ARDS COVID-19 (40-50%) and their ecology seems to have evolved over time, particularly in terms of bacterial resistance. Investigators want to describe and compare this evolution of bacterial and fungal ecology as well as identify potential risk factors that may be associated with these changes in ecology during different waves.

Inclusion Criteria:

• Age > 18 years
• Positive SARS-Cov-2 polymerase chain reaction (PCR)
• healthcare associated pneumonia

Exclusion Criteria : Patient opposition to participate to the study

Patients over 18 years old with a SARS-CoV-2 infection confirmed by positive PCR tests of nasopharyngeal or respiratory secretion samples. In addition, patients included presented a healthcare associated pneumonia according to SFAR(French Society of Anesthesia and Intensive Care) recommendations and based on criteria adapted from the European Centre for Disease Prevention and Control (ECDC) recommendations. Patients who refused their data use were excluded.