* two or more of the following : body temperature higher than 38 celsius, cough of recent onset (in the previous 10 days), dyspnea, odinophagia, malaise, fatigue, acute diarrheal disease. * history of covid-19 confirmed by rt-pcr or igg antibodies * family member with suspected or confirmed covid 19 * cohabitating with a suspected or confirmed case of covid-19 * hepatitis b anti-surface antigen antibodies lower than 10mu/ml at baseline evaluation * acute or chronic hepatitis b * confirmed diagnosis of hiv infection either by clinical history or elisa inmunassay at baseline evaluation * use of tdf/ftc in the last three months for other clinical conditions * alt or ast higher than 2 times the upper reference limit * serum hemoglobin \<11g/dl or neutropenia\<1.000cell/mm3 * renal dysfunction defined as egfr lower than 60ml/min (using the ckdepi formula) or history of chronic kidney disease known hypersensitivity to tdf/ftc serum phosphorus level \<2.5mg/dl * diagnosed osteopenia or osteoporosis * history of pathological fractures * pregnancy, lactation or pregnancy desire during the period of the study * being a participant in another clinical trial of prevention for covid-19 * use of any of the following drugs: cidofovir, celecoxib, diclofenac, ibuprofen, metadon, naproxen, nimesulide, piroxicam, amiodarone, quinine, amikacin, cephalexin, clarithromycin, gentamicin, piperacillin / tazobazorcin, flucomycin, flucomycin, sulfadiazine, vancomycin , ganciclovir, ledipasvir / sofosbuvir, sofosbuvir / velpatasvir, furosemide, hydralazine, sacubitril, verapamil, interferon, hydroxyurea, dolutegravir / lamivudine abacavir, didanosine, lamivudine, atazanavir / cobicistat, atazanavir / ritonavir, darunavir / ritonavir, darunavir / cobicistat, indinavir, interferon, hydroxyurea, cyclosporine, mycophenolate, sirolimus, tacrolimus, acetazolamide orlistat, probenecid, pyridostigmine, sevelamer, zoledronic acid.

* two or more of the following : body temperature higher than 38 celsius, cough of recent onset (in the previous 10 days), dyspnea, odinophagia, malaise, fatigue, acute diarrheal disease. * history of covid-19 confirmed by rt-pcr or igg antibodies * family member with suspected or confirmed covid 19 * cohabitating with a suspected or confirmed case of covid-19 * hepatitis b anti-surface antigen antibodies lower than 10mu/ml at baseline evaluation * acute or chronic hepatitis b * confirmed diagnosis of hiv infection either by clinical history or elisa inmunassay at baseline evaluation * use of tdf/ftc in the last three months for other clinical conditions * alt or ast higher than 2 times the upper reference limit * serum hemoglobin \<11g/dl or neutropenia\<1.000cell/mm3 * renal dysfunction defined as egfr lower than 60ml/min (using the ckdepi formula) or history of chronic kidney disease known hypersensitivity to tdf/ftc serum phosphorus level \<2.5mg/dl * diagnosed osteopenia or osteoporosis * history of pathological fractures * pregnancy, lactation or pregnancy desire during the period of the study * being a participant in another clinical trial of prevention for covid-19 * use of any of the following drugs: cidofovir, celecoxib, diclofenac, ibuprofen, metadon, naproxen, nimesulide, piroxicam, amiodarone, quinine, amikacin, cephalexin, clarithromycin, gentamicin, piperacillin / tazobazorcin, flucomycin, flucomycin, sulfadiazine, vancomycin , ganciclovir, ledipasvir / sofosbuvir, sofosbuvir / velpatasvir, furosemide, hydralazine, sacubitril, verapamil, interferon, hydroxyurea, dolutegravir / lamivudine abacavir, didanosine, lamivudine, atazanavir / cobicistat, atazanavir / ritonavir, darunavir / ritonavir, darunavir / cobicistat, indinavir, interferon, hydroxyurea, cyclosporine, mycophenolate, sirolimus, tacrolimus, acetazolamide orlistat, probenecid, pyridostigmine, sevelamer, zoledronic acid.

- two or more of the following : body temperature higher than 38 celsius, cough of recent onset (in the previous 10 days), dyspnea, odinophagia, malaise, fatigue, acute diarrheal disease. - history of covid-19 confirmed by rt-pcr or igg antibodies - family member with suspected or confirmed covid 19 - cohabitating with a suspected or confirmed case of covid-19 - hepatitis b anti-surface antigen antibodies lower than 10mu/ml at baseline evaluation - acute or chronic hepatitis b - confirmed diagnosis of hiv infection either by clinical history or elisa inmunassay at baseline evaluation - use of tdf/ftc in the last three months for other clinical conditions - alt or ast higher than 2 times the upper reference limit - serum hemoglobin <11g/dl or neutropenia<1.000cell/mm3 - renal dysfunction defined as egfr lower than 60ml/min (using the ckdepi formula) or history of chronic kidney disease known hypersensitivity to tdf/ftc serum phosphorus level <2.5mg/dl - diagnosed osteopenia or osteoporosis - history of pathological fractures - pregnancy, lactation or pregnancy desire during the period of the study - being a participant in another clinical trial of prevention for covid-19 - use of any of the following drugs: cidofovir, celecoxib, diclofenac, ibuprofen, metadon, naproxen, nimesulide, piroxicam, amiodarone, quinine, amikacin, cephalexin, clarithromycin, gentamicin, piperacillin / tazobazorcin, flucomycin, flucomycin, sulfadiazine, vancomycin , ganciclovir, ledipasvir / sofosbuvir, sofosbuvir / velpatasvir, furosemide, hydralazine, sacubitril, verapamil, interferon, hydroxyurea, dolutegravir / lamivudine abacavir, didanosine, lamivudine, atazanavir / cobicistat, atazanavir / ritonavir, darunavir / ritonavir, darunavir / cobicistat, indinavir, interferon, hydroxyurea, cyclosporine, mycophenolate, sirolimus, tacrolimus, acetazolamide orlistat, probenecid, pyridostigmine, sevelamer, zoledronic acid.

- two or more of the following : body temperature higher than 38 celsius, cough of recent onset (in the previous 10 days), dyspnea, odinophagia, malaise, fatigue, acute diarrheal disease. - history of covid-19 confirmed by rt-pcr or igg antibodies - family member with suspected or confirmed covid 19 - cohabitating with a suspected or confirmed case of covid-19 - hepatitis b anti-surface antigen antibodies lower than 10mu/ml at baseline evaluation - acute or chronic hepatitis b - confirmed diagnosis of hiv infection either by clinical history or elisa inmunassay at baseline evaluation - use of tdf/ftc in the last three months for other clinical conditions - alt or ast higher than 2 times the upper reference limit - serum hemoglobin <11g/dl or neutropenia<1.000cell/mm3 - renal dysfunction defined as egfr lower than 60ml/min (using the ckdepi formula) or history of chronic kidney disease known hypersensitivity to tdf/ftc serum phosphorus level <2.5mg/dl - diagnosed osteopenia or osteoporosis - history of pathological fractures - pregnancy, lactation or pregnancy desire during the period of the study - being a participant in another clinical trial of prevention for covid-19 - use of any of the following drugs: cidofovir, celecoxib, diclofenac, ibuprofen, metadon, naproxen, nimesulide, piroxicam, amiodarone, quinine, amikacin, cephalexin, clarithromycin, gentamicin, piperacillin / tazobazorcin, flucomycin, flucomycin, sulfadiazine, vancomycin , ganciclovir, ledipasvir / sofosbuvir, sofosbuvir / velpatasvir, furosemide, hydralazine, sacubitril, verapamil, interferon, hydroxyurea, dolutegravir / lamivudine abacavir, didanosine, lamivudine, atazanavir / cobicistat, atazanavir / ritonavir, darunavir / ritonavir, darunavir / cobicistat, indinavir, interferon, hydroxyurea, cyclosporine, mycophenolate, sirolimus, tacrolimus, acetazolamide orlistat, probenecid, pyridostigmine, sevelamer, zoledronic acid.