The purpose of this study is to evaluate the efficacy and safety of CaD in reducing SARS-CoV-2 viral load in non-hospitalized adult patients diagnosed with COVID-19, documented with a positive SARS-CoV-2 PCR and with the occurrence of COVID-19 symptoms.

This study is a phase II, randomized, double-blind, placebo-controlled, monocenter trial. The study will assess the efficacy and safety of CaD compared to placebo in reducing SARS-CoV-2 viral load in non-hospitalized adult patients diagnosed with COVID-19, as well as monitoring symptoms severity, progression of the disease to severe form, and persistence of symptoms.

The treatment period is seven consecutive days, followed by a 12-weeks observational period without treatment administration.

Enrolled patients will be randomized, in a ratio of 1:1 into the following treatment groups: - IMP arm: patients will receive 2 x 2 capsules of Calcium Dobesilate (CaD) 500 mg (total of 2000 mg) daily for seven consecutive days

- Placebo arm: patients will receive 2 x 2 capsules of matching placebo (Mannitol 500 mg) daily for seven consecutive days.

Inclusion Criteria:

1. Documented COVID-19 diagnosis (SARS-CoV-2 positivity as assessed by PCR) ≤3 days of symptom appearance, with a CT<25.
2. Symptoms related to Day 1 ≤ 5 days.
3. Participant presents at least one of the following acute COVID-19 symptoms: nasal congestion or runny nose, sore throat, headache, myalgia, dry/productive cough, fever, chills, abdominal symptoms (nausea, vomiting, diarrhea, abdominal pain), fatigue, chest pain, palpitations, and shortness of breath.
4. Participant is aged ≥ 16 years of age.
5. Participant has provided an appropriate signed Informed consent.

Exclusion Criteria:

1. Known hypersensitivity or allergy to any of the study products to be administered.
2. Participation in any other investigational device or drug study within 30 days preceding study screening visit.
3. Treatment with Calcium Dobesilate or related molecules (e.g., ethamsylate) within 30 days preceding screening visit, or current treatment with any other investigational agent(s).
4. Breastfeeding, unless If the patient agrees to stop breastfeeding
5. Treatment with any investigational, emergency use authorization-approved, or approved drug for COVID-19, such as, but not limited to: monoclonal antibody treatment, direct or indirect antiviral treatment, and others according to local guidelines.
6. Any kind of disorder or medical conditions that, in the opinion of the investigators, may be associated with increased risk to the participant, may affect patients' compliance, or may interfere with study assessments or outcomes.
7. Inability to follow and comply with study procedures.
8. Participant has hospitalization criteria according to local guidelines (Sat < 95%, RR >25) at the time of screening or is admitted to hospital prior to randomization
9. Participant is, in the opinion of the investigators, likely to deteriorate in the next 24-48h and require hospitalization

The central pharmacy of the HUG is responsible for preparation of the randomization list and of the blinding of the study treatments. Randomization will be done in variable-sized blocks (size 4) in random sequence.

Pharmacists will be un-blinded. Care providers and/or outcome assessors, nurses, clinical research associates, investigators and patients will be blinded. Participants will be allocated to either the treatment group (CaD) or placebo group at Day 1 visit through randomization process, and will be dispensed the full treatment regimen on-site, including instructions on intake and explanations of side-effects.

The investigators will receive from the central pharmacy of the HUG all the study treatments and the participant's allocated treatment randomization number. Thus, the subjects who meet the eligibility criteria will dynamically be randomized at 1:1 ratio and be assigned either to the CaD or to the placebo arms during Day 1 visit.