A Respiratory infection with the SARS-CoV2 virus is associated with a major risk of viral pneumonia that can lead to respiratory distress requiring resuscitation. In the most severe forms, it may require mechanical ventilation or even lead to an acute respiratory distress syndrome with a particularly poor prognosis. The SARS-CoV2 is a single-stranded RNA virus of positive polarity and belongs to the beta genus of Coronaviruses. SARS-CoV2 is responsible for the third epidemic in less than twenty years secondary to a Coronavirus (SARS-CoV then MERS-CoV) and if the mortality associated with it is lower than that of previous strains, notably MERS-CoV, its spread is considerably big. As a result, the number of patients developing respiratory distress requiring invasive mechanical ventilation is high, with prolonged ventilation duration in these situations

Patients requiring invasive mechanical ventilation are at risk of secondary, nosocomial, a hospitalization in the ICU service and can affect up to 40% of ventilated patients. The occurrence of ventilator-associated pneumonia is associated with an increase in the duration of mechanical ventilation and its effect on mortality remains uncertain under general conditions. The mechanisms underlying the occurrence of lower respiratory infection during invasive mechanical ventilation are numerous, depending for the most part on two distinct elements: the occurrence of transcolonisation, which will secondarily promote colonisation of the lower respiratory tract, and the modification of the competence of the immune system in its response to aggression by microbial agents whose pathogenicity is highly variable.

Throughout the infection by SARS-CoV2, the theoretical risk of secondary respiratory infection during mechanical ventilation is important due to the intrication of three concomitant phenomena: direct pulmonary aggression, which will alter the functionality of local immunity, the "cytokinic storm", responsible for the severity of the respiratory picture that motivated intubation and the need for mechanical ventilation leading inevitably to transcolonisation. Despite all of these pathophysiological arguments, very little data are available on the possibility of secondary low respiratory tract infection occurring during SARS-CoV2 infection and more generally during Coronarivus infections. even though all of these elements are well known and widely studied, very little data are currently available on the potential interaction between Coronaviruses and bacteria. The importance of this issue is very significant as recent observations tend to show a relative rarity of the occurrence of secondary lung infections during mechanical ventilation and the population of smokers, subject to chronic obstructive bronchitis (usually particularly susceptible to bacterial superinfections), does not appear to be more affected than that of non-smokers although the current data are very partial.

The research is prospective, non interventional study that involves patients suffering from another severe form a COVID-19 infection: the nosocomial pneumonia under mechanical ventilation

Inclusion Criteria:

• Patient whose age ≥ 18 years old
• French-speaking patient
• Patient whose COVID-19 infection was diagnosed by either a laboratory test, PCR or any other commercial or public health test.
• Adult acute respiratory distress syndrome according to the Berlin definition
• Pneumonia acquired under mechanical ventilation defined according to the criteria of international companies

Exclusion Criteria:

• Patient/family or proxy opposing participation in the study
• Patient under guardianship or curatorship
• Patient deprived of liberty
• Patient under the safeguard of justice.

Patient aged over 18 years, infected by the COVID-19 with a severe form of pneumonia especially the nosocomial pneumonia acquired under mechanical ventilation.