Covid-19 disease is one of the most important health system challenges which is the result of the recent SARS CoV-2 virus outbreak. So far, despite the use of different types of pharmaceuticals, none has been served as a curative treatment and research is continued to find one or more effective drugs; either palliative or curative ones.

One of the most important clinical problems in Covid-19 patients is lung involvement, which may causes significant sequels; leading to a main part of morbidity and/or mortality.

Surfactant is one of the drugs that can have valuable effects on the lungs, both by reducing the alveolar surface tension and by exerting immunomodulatory effects.

In a previous study by the same team, favorable effects were seen in intubated patients; however, the aim of this study was to evaluate the effect of exogenous nebulized surfactant in the pre-intubation stages of the disease.

Exogenous surfactant in neonates with clinical pulmonary distress syndrome has demonstrated pulmonary improvement; the latter being one of the most important applications of exogenous surfactant. In adults with underlying lung disease, especially Adult Respiratory Distress Syndrome (ARDS), there are controversial findings regarding the efficacy of surfactant.

However, in a previous study, it was shown that surfactant in COVID-19 patients with pulmonary intubation improved pulmonary function and gas exchange and also, reduced patient mortality.

However, none of the other repurposed drugs in COVID-19 have yet been able to prove significant effects in the treatment of patients; based on a recent study on more than 11000 COVID-19 patients (i.e. the SOLIDARITY study).

Due to the significant worldwide challnege with COVID-19, many efforts have been made in this regard, but the definitive cure has not yet been obtained, and therefore, efforts are being made to find an effective method to treat the disease and improve patients' symptoms; parallel to the efforts to increase the vaccination coverage.

Inclusion Criteria:

• age over 18 years
• definitive proof of COVID-19 infection by polymerase chain reaction (PCR) within 48 hours of hospital admission
• COVID-19 related Moderate ARDS following Berlin criteria definition with PaO2/FiO2 < 200 requiring what condition?
• Signed and dated informed consent form (ICF) by the subject or caregivers

Exclusion Criteria:

• known or high suspicion of pre-existing heart failure, unstable angina
• presence of severe shock with hemodynamic instability despite escalating vasopressors
• Severe, underlying pulmonary infection or severe pulmonary disease except for COVID-19 (COPD, pulmonary fibrosis, lung cancer, bacterial pneumonia, etc.)
• Diagnosis of pulmonary hemorrhage
• Pregnancy or lactation
• Other significant cause than ARDS to the respiratory failure
• Age less than 18
• Age more than 80
• Need for ECMO (extracorporeal membrane oxygenation) during the study
• Anticipated transfer to another hospital within 72 hours
• Known hypersensitivity to exogenous surfactant
• Current participation or participation in another study within the last month that in the opinion of the investigator would prevent enrollment for safety purposes

to be determined

The outcome assessor would be blind regarding the study groups