This study is a multicenter, prospective, placebo-controlled, comparative, randomized, double-blind local phase II clinical trial. Duration of study is 18 months. In the study, patients will be randomized in a ratio of 1: 1 into two arms, standard medical therapy + placebo versus standard medical therapy + inhaled Aviptadil arms. Randomization will be carried out by the block randomization method. In the event that patients need intensive care in the study, the patients will be taken into intensive care unit and excluded from the study and their treatment will be continued in the intensive care unit as deemed appropriate by the physician and it is foreseen that inhaled Aviptadil will be used for a period of minimum 7 and maximum 14 days. Aviptadil will be discontinued in patients who do not heal after 14 days. This study includes 8 visits, consisting of a total of 7 physical visits and 1 phone follow-up visit. The study period will be 6 months for each patient. Patient recruitment is planned to take 12 months. Study centers will be asked to use investigational products for their patients who sign the informed consent form for 12 months. The study population will consist of patients 18 years of age and older with COVID-19 pulmonary involvement and hospitalized patients.

Inclusion Criteria:

1.18 years and older women or men, under 70 years old

2.Patients with positive SARS-CoV-2 real time PCR result and an appearance in line with COVID-19 pneumonia on thorax CT

3. Need for oxygen support or SpO2 <94 in room air

4. Patients who can use a nebulizer (with assistance when necessary)

5.Patients who are willing and capable (mentally and physically) who can sign a written informed consent form, to participate in all aspects of the study, to participate in the planned visits and to comply with the terms of the protocol.

Exclusion Criteria:

1. Intensive care admission

2. The need for mechanical ventilation

3. Patients with previously known organ (kidney, heart and liver) failure

   * To be determined as previously known heart failure (EF <30), previously known liver failure (Child-Pugh C) and previously known renal failure (Cr.clerance <30).

4. COVID-19 disease with no indication for hospitalization

5. Participants in another clinical trial

6. Pregnancy or lactation

7. Solid organ or stem cell transplantation story

8. Patients with collagen tissue disease

9. Use of immunosuppressive therapy

10. Procalcitonin ≥2 (baseline visit)

11. Under 18 years old

12. Those who had myocardial infarction in the last 3 months

13. Those who do not have the capacity to understand the possible results, scope and nature of the study due to legal insufficiency and / or other reasons.

14. Those who, in the opinion of the investigator, cannot continue the treatment protocol regularly or cannot cooperate

15. Presence of malignancy

16. Patients with neurological diseases

Double-blind