Clinical research focused to evaluate the effect as coadyuvant of a combination of L. plantarum and P. acidilactici in adults positive for SARS-CoV-2 with mild clinical COVID-19 symptoms. Main objective is to evaluate how this combination of probiotics reduce the risk to progress to moderate or severe COVID and associated advantages such as reduce the risk of death. Adittionnally this RCT is launching to explore the benefits of this combination of strains to modulate fecal microbiome and explore how this correlate with clinical improvement.

Randomized controlled trial (RCT) to evaluate safety and efficacy of Lactobacillus plantarum CECT 30292, Lactobacillus plantarum CECT 7484, Lactobacillus plantarum CECT 7485 y P. acidilactici CECT 7483, one dose a day to reduce the risk of subjects with mild COVID-19 to evolute to moderate or severe disease. As secondary aims this trial is intented to evaluate the effect of this strains combinations to reduce the frequency and severity of gastrointestinal COVID-19 symptoms and lung abnormalities, to reduce the viral load, modulate the levels of IgG/IgM, and positively modify the fecal microbiota.

300 adults, 18 to 60 years, RTq-PCR positive for SARS-CoV-2, with mild COVID-19, and SpO2 > 90%, living in Mexico city (2,200m over the sea level) will be randomized, after sign of informed consent to receive a combintation of Lactobacillus plantarum CECT 30292, Lactobacillus plantarum CECT 7484, Lactobacillus plantarum CECT 7485 y P. acidilactici CECT 7483 one a day orally or placebo for 30 days.

Clinical severity, lung abnormalities (x-rays), viral load, IgG/IgM levels, and fecal microbiome will be evaluated at COVID-19 research center before randomization. Participants will be invited to remain at home and clinical evolution, temperature, SpO2 will be recorder and reported remotely during the 30 days intervention.

On days 15 and 30, participants will be invited to return to COVID-19 research center to take samples to evaluate evolution of viral load, IgG/IgM and fecal microbiome.

During the 30-days intervention period outcomes such as clinical progression, need of hospitalization, admission to Intensive Care Unit and death will be evaluated

Inclusion Criteria:

• Women or men, >18y to 60 years
• RTq-PCR to COVID positive
• Presence of cough, fever, dyspnoea, or headache, onset <= 7 days
• Mild severity of COVID-19
• Peripheral Oxygen Saturation (SpO2) >90%
• Able to read, understand and sign the informed consent
• To have at least one family member to collaborate with the follow-up in the clinical findings at beginning and throughout of the study.

Exclusion Criteria:

• Severe Obesity (BMI>40)
• Uncontrolled Type II diabetes (HbA1C >8.0)
• Uncontrolled systolic hypertension (>160mmdeHg)
• Acute pancreatitis
• Chronic diarrhea or constipation
• Inflammatory bowel disease
• Blood clotting disease
• Immunosuppression derived from Cancer, post-transplantation, auto-immune disease or HIV
• Severe and active seasonal allergies
• Pregnancy or lactation
• Glucose 6P-dehydrogenase deficiency
• Regular use of probiotic or antibiotic within 2 weeks before entering the trial
• Severe or uncontrolled Chronic Respiratory Diseases (Asthma, COPD or Cystic Fibrosis)

Deidentified individual patient data (IPD), together with data dictionary defining each field in the set, will be made public upon any formal requests with a defined analysis plan.

From the moment of manuscript publication, without time limit.

Formal request with a defined analysis plan. Please contact espadaler@ab-biotics.com or medical@ab-biotics.com

All study staff, including the Principal Investigator and the persons performing the subject assessments, will be blinded during the study. Sealed individual treatment code envelopes will be kept at the clinic to be able to break the code if any emergency occurs, as judged by the Investigator