1. women who are pregnant or breastfeeding at the time of enrolment 2. weight \<40kg. 3. evidence of current liver disease (ast/alt \>3x uln ; total bilirubin\>3xuln or prior history of cirrhosis or other chronic liver disease) 4. renal dysfunction as evidenced by an estimated glomerular filtration rate (egfr) \<60ml/min, or prior/current diagnosis of chronic kidney disease. 5. prior receipt of any treatment with putative or proven anti-sars-cov-2 activity apart from the following: chloroquine, hydroxychloroquine, or ritonavir/lopinavir initiated no more than 12 hours prior to first receipt of tzv/placebo for this trial. antiretrovirals initiated prior to admission as treatment for hiv, supportive, steroidal and non-steroidal anti-inflammatory, or anti-pyretic treatments are allowed. 6. indication for immediate initiation of antiretroviral therapy in hiv-infected patients, who are unable to delay art initiation or re-initiation until the treatment phase of this study is complete. 7. permanently lives or works more than 120km from the hospital where recruited 8. unable to provide own consent 9. in the opinion of either the attending doctor, or a study investigator that the patient is not a candidate for a clinical trial 10. receipt of anti-epileptic medication, warfarin or tb treatment at the time of recruitment or during the receipt of trial treatment. 11. enrolled currently in a trial of novel preventive treatment or treatment of sars-cov-2. 12. potential participants who are investigational site staff members, or relatives of a site staff member, or those who are employees of pharmacentrix involved in the conduct of the trial. -

1. women who are pregnant or breastfeeding at the time of enrolment 2. weight \<40kg. 3. evidence of current liver disease (ast/alt \>3x uln ; total bilirubin\>3xuln or prior history of cirrhosis or other chronic liver disease) 4. renal dysfunction as evidenced by an estimated glomerular filtration rate (egfr) \<60ml/min, or prior/current diagnosis of chronic kidney disease. 5. prior receipt of any treatment with putative or proven anti-sars-cov-2 activity apart from the following: chloroquine, hydroxychloroquine, or ritonavir/lopinavir initiated no more than 12 hours prior to first receipt of tzv/placebo for this trial. antiretrovirals initiated prior to admission as treatment for hiv, supportive, steroidal and non-steroidal anti-inflammatory, or anti-pyretic treatments are allowed. 6. indication for immediate initiation of antiretroviral therapy in hiv-infected patients, who are unable to delay art initiation or re-initiation until the treatment phase of this study is complete. 7. permanently lives or works more than 120km from the hospital where recruited 8. unable to provide own consent 9. in the opinion of either the attending doctor, or a study investigator that the patient is not a candidate for a clinical trial 10. receipt of anti-epileptic medication, warfarin or tb treatment at the time of recruitment or during the receipt of trial treatment. 11. enrolled currently in a trial of novel preventive treatment or treatment of sars-cov-2. 12. potential participants who are investigational site staff members, or relatives of a site staff member, or those who are employees of pharmacentrix involved in the conduct of the trial. -

women who are pregnant or breastfeeding at the time of enrolment weight <40kg. evidence of current liver disease (ast/alt >3x uln ; total bilirubin>3xuln or prior history of cirrhosis or other chronic liver disease) renal dysfunction as evidenced by an estimated glomerular filtration rate (egfr) <60ml/min, or prior/current diagnosis of chronic kidney disease. prior receipt of any treatment with putative or proven anti-sars-cov-2 activity apart from the following: chloroquine, hydroxychloroquine, or ritonavir/lopinavir initiated no more than 12 hours prior to first receipt of tzv/placebo for this trial. antiretrovirals initiated prior to admission as treatment for hiv, supportive, steroidal and non-steroidal anti-inflammatory, or anti-pyretic treatments are allowed. indication for immediate initiation of antiretroviral therapy in hiv-infected patients, who are unable to delay art initiation or re-initiation until the treatment phase of this study is complete. permanently lives or works more than 120km from the hospital where recruited unable to provide own consent in the opinion of either the attending doctor, or a study investigator that the patient is not a candidate for a clinical trial receipt of anti-epileptic medication, warfarin or tb treatment at the time of recruitment or during the receipt of trial treatment. enrolled currently in a trial of novel preventive treatment or treatment of sars-cov-2. potential participants who are investigational site staff members, or relatives of a site staff member, or those who are employees of pharmacentrix involved in the conduct of the trial. -

women who are pregnant or breastfeeding at the time of enrolment weight <40kg. evidence of current liver disease (ast/alt >3x uln ; total bilirubin>3xuln or prior history of cirrhosis or other chronic liver disease) renal dysfunction as evidenced by an estimated glomerular filtration rate (egfr) <60ml/min, or prior/current diagnosis of chronic kidney disease. prior receipt of any treatment with putative or proven anti-sars-cov-2 activity apart from the following: chloroquine, hydroxychloroquine, or ritonavir/lopinavir initiated no more than 12 hours prior to first receipt of tzv/placebo for this trial. antiretrovirals initiated prior to admission as treatment for hiv, supportive, steroidal and non-steroidal anti-inflammatory, or anti-pyretic treatments are allowed. indication for immediate initiation of antiretroviral therapy in hiv-infected patients, who are unable to delay art initiation or re-initiation until the treatment phase of this study is complete. permanently lives or works more than 120km from the hospital where recruited unable to provide own consent in the opinion of either the attending doctor, or a study investigator that the patient is not a candidate for a clinical trial receipt of anti-epileptic medication, warfarin or tb treatment at the time of recruitment or during the receipt of trial treatment. enrolled currently in a trial of novel preventive treatment or treatment of sars-cov-2. potential participants who are investigational site staff members, or relatives of a site staff member, or those who are employees of pharmacentrix involved in the conduct of the trial. -

1. women who are pregnant or breastfeeding at the time of enrolment 2. weight <40kg. 3. evidence of current liver disease (ast/alt >3x uln ; total bilirubin>3xuln or prior history of cirrhosis or other chronic liver disease) 4. renal dysfunction as evidenced by an estimated glomerular filtration rate (egfr) <60ml/min, or prior/current diagnosis of chronic kidney disease. 5. prior receipt of any treatment with putative or proven anti-sars-cov-2 activity apart from the following: chloroquine, hydroxychloroquine, or ritonavir/lopinavir initiated no more than 12 hours prior to first receipt of tzv/placebo for this trial. antiretrovirals initiated prior to admission as treatment for hiv, supportive, steroidal and non-steroidal anti-inflammatory, or anti-pyretic treatments are allowed. 6. indication for immediate initiation of antiretroviral therapy in hiv-infected patients, who are unable to delay art initiation or re-initiation until the treatment phase of this study is complete. 7. permanently lives or works more than 120km from the hospital where recruited 8. unable to provide own consent 9. in the opinion of either the attending doctor, or a study investigator that the patient is not a candidate for a clinical trial 10. receipt of anti-epileptic medication, warfarin or tb treatment at the time of recruitment or during the receipt of trial treatment. 11. enrolled currently in a trial of novel preventive treatment or treatment of sars-cov-2. 12. potential participants who are investigational site staff members, or relatives of a site staff member, or those who are employees of pharmacentrix involved in the conduct of the trial. -

1. women who are pregnant or breastfeeding at the time of enrolment 2. weight <40kg. 3. evidence of current liver disease (ast/alt >3x uln ; total bilirubin>3xuln or prior history of cirrhosis or other chronic liver disease) 4. renal dysfunction as evidenced by an estimated glomerular filtration rate (egfr) <60ml/min, or prior/current diagnosis of chronic kidney disease. 5. prior receipt of any treatment with putative or proven anti-sars-cov-2 activity apart from the following: chloroquine, hydroxychloroquine, or ritonavir/lopinavir initiated no more than 12 hours prior to first receipt of tzv/placebo for this trial. antiretrovirals initiated prior to admission as treatment for hiv, supportive, steroidal and non-steroidal anti-inflammatory, or anti-pyretic treatments are allowed. 6. indication for immediate initiation of antiretroviral therapy in hiv-infected patients, who are unable to delay art initiation or re-initiation until the treatment phase of this study is complete. 7. permanently lives or works more than 120km from the hospital where recruited 8. unable to provide own consent 9. in the opinion of either the attending doctor, or a study investigator that the patient is not a candidate for a clinical trial 10. receipt of anti-epileptic medication, warfarin or tb treatment at the time of recruitment or during the receipt of trial treatment. 11. enrolled currently in a trial of novel preventive treatment or treatment of sars-cov-2. 12. potential participants who are investigational site staff members, or relatives of a site staff member, or those who are employees of pharmacentrix involved in the conduct of the trial. -