inclusion criteria: * positive laboratory test for active sars-cov-2 viral infection based on local laboratory standard (i.e. +pcr) within 3 days of randomization. * no known history of confirmed sars-cov-2 infection * bmi \>= 25kg/m2 by self-report height/weight or \>= 23kg/m2 in patients who self-identify in south asian or latinx background. * willing and able to comply with study procedures (i.e. swallow pills) * has an address and electronic device for communication * gfr\>45ml/min within 2 weeks for patients \>75 years old, or with history of heart, kidney, or liver failure.

inclusion criteria: * positive laboratory test for active sars-cov-2 viral infection based on local laboratory standard (i.e. +pcr) within 3 days of randomization. * no known history of confirmed sars-cov-2 infection * bmi \>= 25kg/m2 by self-report height/weight or \>= 23kg/m2 in patients who self-identify in south asian or latinx background. * willing and able to comply with study procedures (i.e. swallow pills) * has an address and electronic device for communication * gfr\>45ml/min within 2 weeks for patients \>75 years old, or with history of heart, kidney, or liver failure.

inclusion criteria: - positive laboratory test for active sars-cov-2 viral infection based on local laboratory standard (i.e. +pcr) within 3 days of randomization. - no known history of confirmed sars-cov-2 infection - bmi >= 25kg/m2 by self-report height/weight or >= 23kg/m2 in patients who self-identify in south asian or latinx background. - willing and able to comply with study procedures (i.e. swallow pills) - has an address and electronic device for communication - gfr>45ml/min within 2 weeks for patients >75 years old, or with history of heart, kidney, or liver failure.

inclusion criteria: - positive laboratory test for active sars-cov-2 viral infection based on local laboratory standard (i.e. +pcr) within 3 days of randomization. - no known history of confirmed sars-cov-2 infection - bmi >= 25kg/m2 by self-report height/weight or >= 23kg/m2 in patients who self-identify in south asian or latinx background. - willing and able to comply with study procedures (i.e. swallow pills) - has an address and electronic device for communication - gfr>45ml/min within 2 weeks for patients >75 years old, or with history of heart, kidney, or liver failure.

inclusion criteria, stage 1 treatment trial: - positive laboratory test for active sars-cov-2 viral infection based on local laboratory standard (i.e. +pcr) within 3 days of randomization; negative antibody test not required. - age >=30 years and < 85 years - gfr>45ml/min within 2 weeks of enrollment or after enrollment - patient has medical record visible within the ehr of participating sites - bmi >= 25kg/m2 by self-report height/weight or >= 23kg/m2 in patients who self-identify in s. asian or latinx background.59-61 - willing and able to comply with study procedures - has an address and electronic device for communication exclusion criteria, stage 1 treatment trial: - symptom onset greater than 7 days before randomization (symptoms not required for inclusion). - currently taking metformin - estimated glomerular filtration rate (egfr) of < 45ml/min/1.73 m2 - electronic medical record history of severe liver disease - other liver disease that in the opinion of the investigator, would affect metformin clearance - documented ast or alt > 3 times the upper limit of normal within 3 months of randomization (if available in electronic medical record) - ehr of nyha stage 3 or 4 heart failure - inability to obtain informed consent - enrollment in another blinded rct for covid - alcohol use disorder - hospitalized, for covid-19 or other reasons. - metformin: electronic history of severe kidney disease, other kidney disease that in the opinion of the investigator would affect clearance, unstable heart failure (stage 3 or 4), allergic reaction to metformin in the past - metformin participants taking these medications: cimetidine, hydroxychloroquine, insulin, sulfonylurea, dolutegravir, patiromer, ranolazine, tafenoquine - fluvoxamine: bipolar disease, allergic reaction to fluvoxamine in the past - fluvoxamine participants taking these medications: rasagiline, selegiline, monoamine oxidase inhibitors, linezolid, duloxetine, methylene blue, tizanidine, ramelteon, alosetron, agomelatine, bromopride, dapoxetine, tasimelteon, thioridazine, urokinase, pimozide - ivermectin: allergic reaction to ivermectin in the past, current loa loa or onchocerciasis infection, typhoid, bcg, or cholera vaccination within the past 14-days or 3 days after - ivermectin participants taking sodium picosulfate

inclusion criteria, stage 1 treatment trial: - positive laboratory test for active sars-cov-2 viral infection based on local laboratory standard (i.e. +pcr) within 3 days of randomization; negative antibody test not required. - age >=30 years and < 85 years - gfr>45ml/min within 2 weeks of enrollment or after enrollment - patient has medical record visible within the ehr of participating sites - bmi >= 25kg/m2 by self-report height/weight or >= 23kg/m2 in patients who self-identify in s. asian or latinx background.59-61 - willing and able to comply with study procedures - has an address and electronic device for communication exclusion criteria, stage 1 treatment trial: - symptom onset greater than 7 days before randomization (symptoms not required for inclusion). - currently taking metformin - estimated glomerular filtration rate (egfr) of < 45ml/min/1.73 m2 - electronic medical record history of severe liver disease - other liver disease that in the opinion of the investigator, would affect metformin clearance - documented ast or alt > 3 times the upper limit of normal within 3 months of randomization (if available in electronic medical record) - ehr of nyha stage 3 or 4 heart failure - inability to obtain informed consent - enrollment in another blinded rct for covid - alcohol use disorder - hospitalized, for covid-19 or other reasons. - metformin: electronic history of severe kidney disease, other kidney disease that in the opinion of the investigator would affect clearance, unstable heart failure (stage 3 or 4), allergic reaction to metformin in the past - metformin participants taking these medications: cimetidine, hydroxychloroquine, insulin, sulfonylurea, dolutegravir, patiromer, ranolazine, tafenoquine - fluvoxamine: bipolar disease, allergic reaction to fluvoxamine in the past - fluvoxamine participants taking these medications: rasagiline, selegiline, monoamine oxidase inhibitors, linezolid, duloxetine, methylene blue, tizanidine, ramelteon, alosetron, agomelatine, bromopride, dapoxetine, tasimelteon, thioridazine, urokinase, pimozide - ivermectin: allergic reaction to ivermectin in the past, current loa loa or onchocerciasis infection, typhoid, bcg, or cholera vaccination within the past 14-days or 3 days after - ivermectin participants taking sodium picosulfate

inclusion criteria, stage 1 treatment trial: - positive laboratory test for active sars-cov-2 viral infection based on local laboratory standard (i.e. +pcr) within 3 days of randomization; negative antibody test not required. - age >=30 years and < 85 years - gfr>45ml/min within 2 weeks of enrollment or after enrollment - patient has medical record visible within the ehr of participating sites - bmi >= 25kg/m2 by self-report height/weight or >= 23kg/m2 in patients who self-identify in s. asian or latinx background.59-61 - willing and able to comply with study procedures - has an address and electronic device for communication exclusion criteria, stage 1 treatment trial: - symptom onset greater than 7 days before randomization (symptoms not required for inclusion). - currently taking metformin - electronic medical record history of kidney disease, i.e.: - estimated glomerular filtration rate (egfr) of < 45ml/min/1.73 m2 - other kidney disease that in the opinion of the investigator would affect clearance - electronic medical record history of severe liver disease - other liver disease that in the opinion of the investigator, would affect metformin clearance - documented ast or alt > 3 times the upper limit of normal within 3 months of randomization (if available in electronic medical record) - ehr of nyha stage 3 or 4 heart failure - inability to obtain informed consent - enrollment in another blinded rct for covid - alcohol use disorder - patients taking these medications: cimetidine, hydroxychloroquine, insulin, sulfonylurea, dolutegravir, patiromer, ranolazine, tafenoquine - hospitalized, for covid-19 or other reasons.

inclusion criteria, stage 1 treatment trial: - positive laboratory test for active sars-cov-2 viral infection based on local laboratory standard (i.e. +pcr) within 3 days of randomization; negative antibody test not required. - age >=30 years and < 85 years - gfr>45ml/min within 2 weeks of enrollment or after enrollment - patient has medical record visible within the ehr of participating sites - bmi >= 25kg/m2 by self-report height/weight or >= 23kg/m2 in patients who self-identify in s. asian or latinx background.59-61 - willing and able to comply with study procedures - has an address and electronic device for communication exclusion criteria, stage 1 treatment trial: - symptom onset greater than 7 days before randomization (symptoms not required for inclusion). - currently taking metformin - electronic medical record history of kidney disease, i.e.: - estimated glomerular filtration rate (egfr) of < 45ml/min/1.73 m2 - other kidney disease that in the opinion of the investigator would affect clearance - electronic medical record history of severe liver disease - other liver disease that in the opinion of the investigator, would affect metformin clearance - documented ast or alt > 3 times the upper limit of normal within 3 months of randomization (if available in electronic medical record) - ehr of nyha stage 3 or 4 heart failure - inability to obtain informed consent - enrollment in another blinded rct for covid - alcohol use disorder - patients taking these medications: cimetidine, hydroxychloroquine, insulin, sulfonylurea, dolutegravir, patiromer, ranolazine, tafenoquine - hospitalized, for covid-19 or other reasons.

inclusion criteria, stage 1 treatment trial: - positive laboratory test for active sars-cov-2 viral infection based on local laboratory standard (i.e. +pcr) within 3 days of randomization; negative antibody test not required. - age >=30 years and < 85 years - gfr>45ml/min within 2 weeks of enrollment - patient has medical record visible within the ehr of participating sites - bmi >= 25kg/m2 by self-report height/weight or >= 23kg/m2 in patients who self-identify in s. asian or latinx background.59-61 - willing and able to comply with study procedures - has an address and electronic device for communication exclusion criteria, stage 1 treatment trial: - symptom onset greater than 7 days before randomization (symptoms not required for inclusion). - currently taking metformin - electronic medical record history of kidney disease, i.e.: - estimated glomerular filtration rate (egfr) of < 45ml/min/1.73 m2 - other kidney disease that in the opinion of the investigator would affect clearance - electronic medical record history of severe liver disease - other liver disease that in the opinion of the investigator, would affect metformin clearance - documented ast or alt > 3 times the upper limit of normal within 3 months of randomization (if available in electronic medical record) - ehr of nyha stage 3 or 4 heart failure - inability to obtain informed consent - enrollment in another blinded rct for covid - alcohol use disorder - patients taking these medications: cimetidine, hydroxychloroquine, insulin, sulfonylurea, dolutegravir, patiromer, ranolazine, tafenoquine - hospitalized, for covid-19 or other reasons.

inclusion criteria, stage 1 treatment trial: - positive laboratory test for active sars-cov-2 viral infection based on local laboratory standard (i.e. +pcr) within 3 days of randomization; negative antibody test not required. - age >=30 years and < 85 years - gfr>45ml/min within 2 weeks of enrollment - patient has medical record visible within the ehr of participating sites - bmi >= 25kg/m2 by self-report height/weight or >= 23kg/m2 in patients who self-identify in s. asian or latinx background.59-61 - willing and able to comply with study procedures - has an address and electronic device for communication exclusion criteria, stage 1 treatment trial: - symptom onset greater than 7 days before randomization (symptoms not required for inclusion). - currently taking metformin - electronic medical record history of kidney disease, i.e.: - estimated glomerular filtration rate (egfr) of < 45ml/min/1.73 m2 - other kidney disease that in the opinion of the investigator would affect clearance - electronic medical record history of severe liver disease - other liver disease that in the opinion of the investigator, would affect metformin clearance - documented ast or alt > 3 times the upper limit of normal within 3 months of randomization (if available in electronic medical record) - ehr of nyha stage 3 or 4 heart failure - inability to obtain informed consent - enrollment in another blinded rct for covid - alcohol use disorder - patients taking these medications: cimetidine, hydroxychloroquine, insulin, sulfonylurea, dolutegravir, patiromer, ranolazine, tafenoquine - hospitalized, for covid-19 or other reasons.

inclusion criteria: prevention arm: - negative igm, igg antibody for sars-cov-2 - glomerular filtration rate (gfr) > 45ml/min/1.73 m2 - patient has medical record visible within the electronic health record (ehr) program of participating sites - body mass index (bmi) >= 25kg/m2 by self-report height/weight or >= 23kg/m2 in patients who self-identify as south asian or latinx treatment arm: - positive laboratory test for active sars-cov-2 viral infection based on local laboratory standard (+pcr) - glomerular filtration rate (gfr) > 45ml/min/1.73 m2 - patient has medical record visible within the electronic health record (ehr) program of participating sites - body mass index (bmi) >= 25kg/m2 by self-report height/weight or >= 23kg/m2 in patients who self-identify as south asian or latinx

inclusion criteria: prevention arm: - negative igm, igg antibody for sars-cov-2 - glomerular filtration rate (gfr) > 45ml/min/1.73 m2 - patient has medical record visible within the electronic health record (ehr) program of participating sites - body mass index (bmi) >= 25kg/m2 by self-report height/weight or >= 23kg/m2 in patients who self-identify as south asian or latinx treatment arm: - positive laboratory test for active sars-cov-2 viral infection based on local laboratory standard (+pcr) - glomerular filtration rate (gfr) > 45ml/min/1.73 m2 - patient has medical record visible within the electronic health record (ehr) program of participating sites - body mass index (bmi) >= 25kg/m2 by self-report height/weight or >= 23kg/m2 in patients who self-identify as south asian or latinx