This is a double-blind, multicentre, multinational study to evaluate the safety and collect preliminary efficacy data of Codivir drug product in 130 hospitalized adults with moderate COVID-19 symptoms. COVID-19 symptoms (fever, cough, myalgia and changes in smell or taste) onset must be within 7 days prior enrolment. Treatment will begin in the hospital, participants will be discharged according to medical decision and continue the treatment until to Day 7 at home and followed up to day 28.

eligible hospitalized participants will be recruited to the study and will receive standard of care treatments as well as Codivir or placebo, which will be administered at a dose of 20 mg SC, twice a day, for 7 days. If up to medical decision of the medical staff in the site, the patient should be released before Day 7, site study team will contact the medical monitor of the study to get the instructions. Participants will be followed up to the 28th day via phone contact. The phone visit will be performed to monitor the clinical symptoms, collect adverse events and concomitant medication and provide the patient with additional instructions, if relevant.

If they have progressed well, they will continue the treatment up to Day 7 at home, receiving a nurse's home visit twice a day to administer Codivir and collect vital signs. Participants will be followed up to Day 28 by telemedicine. A doctor will call them periodically to monitor the clinical evolution, collect adverse events, concomitant medication and instruct the participants. In case of unfavorable evolution, the participants will remain hospitalized receiving the appropriate care. The investigator will decide whether or not the investigational medication will continue, considering the participant's health and well-being.

Inclusion Criteria:

• Age between 18 and 75 years

• Male or female

• SARS-CoV-2 infection indicated by confirmed RT-PCR test

• Moderate hospitalized COVID-19 (at least two out of three criterias below):

  • Evidence of lower respiratory disease during clinical assessment (cough, fever, difficulty breathing) or imaging (X-rays)
  • Oxygen saturation (SpO2) in room air < 93%
  • <30 breaths per minute

• No signs of hemodynamic decompensation

• Absence of pregnancy in women of childbearing age

• Ability to understand and comply with the requirements of the protocol

• Consent to participate

• Consent to use at least one highly effective contraception methods (condoms, IUD, oral contraceptives) since the ICF signature and at least 30 days after the study.

Exclusion Criteria:

• Patients receiving oxygen supplementation except of nasal prongs, nasal intermittent positive pressure ventilation (NIPPV) or high flow nasal cannula (HFNC) that are allowed to be enrolled to the study).
• Positive RT-PCR test more than 72 hours prior to enrolment.
• Onset of symptoms more than 7 days prior to enrolment.
• Participant using drugs that are under clinical investigation in last 30 days.
• Body mass index less than 19.9 or greater than 35.
• Comorbidities such as: other serious infections, active malignancies, autoimmune diseases, liver, kidney or heart failure; another systemic disease and / or laboratory abnormality, which, in the investigator's opinion, prevent the patient from participating in the study.
• Concomitant HIV, HBV or HCV infection.
• Pregnancy or lactation.
• Vaccination for any other infection in the 4 weeks prior to enrolment.
• Any condition that increases the risk of participating in the study, in the opinion of the investigator.

the study is a double-blind study: neither the participants nor the investigators will be aware of arm allocation of each study participant. Blindness is important to avoid bias. Monitoring and reporting of the success of blindness are important for the reader's confidence of the trial results. Groups should be marked by capital letter and blindness should maintain throughout the study.