* persons with any clinical sign or symptoms suggestive of moderate or severe systemic illness with covid-19, including the following: 1. shortness of breath at rest, 2. resting pulse ≥90 beats per minute, 3. resting respiratory rate ≥20 breaths per minute, or 4. oxygen saturation ≤ 93% on room air at sea level. * persons who have not been fully vaccinated against sars-cov-2 and are at high risk of progressing to severe covid-19 illness due to having one of the following underlying conditions and/or sociodemographic risk factors: 1. age ≥ 55 years (with or without comorbidities), 2. body mass index (bmi) ≥30 kg/m² if ≥ 18 years of age or bmi ≥85th percentile for age and gender based on cdc growth charts, 3. chronic kidney disease, 4. diabetes, 5. cardiovascular disease (including congenital heart disease) or hypertension, 6. chronic lung disease (e.g., chronic obstructive pulmonary disease, moderate-to-severe asthma, interstitial lung disease, cystic fibrosis, pulmonary hypertension), 7. sickle cell disease, 8. neurodevelopmental disorders or other conditions that confer medical complexity. * subjects with immunosuppressive disease or receiving immunosuppressive treatment regardless of sars-cov-2 vaccination status. * subjects with active respiratory allergies or subjects expected to require anti-allergy medications during the study period for respiratory allergies. * females of childbearing potential who are either pregnant or sexually active without the use of birth control. * subjects residing in the same household with another subject participating in the study. * treatment with any investigational drug or vaccine therapy within 30 days prior to screening and willing to avoid them during the course of the study. * subjects who have received within the past 90 days or are expected to receive during the study period monoclonal antibody treatment or convalescent covid-19 plasma for covid-19. * receipt of any dose of ntz within seven days prior to screening. * known sensitivity to ntz or any of the excipients comprising the study medication. * subjects unable to swallow oral tablets or capsules. * subjects with known severe heart, lung, neurological or other systemic disease that the investigator believes could preclude safe participation. * subjects likely or expected to require hospitalization unrelated to covid-19 during the study period. * subjects taking medications considered to be major cyp2c8 substrates. * subjects who, in the judgment of the investigator, will be unlikely to comply with the requirements of this protocol including completion of the subject diary.

* persons with any clinical sign or symptoms suggestive of moderate or severe systemic illness with covid-19, including the following: 1. shortness of breath at rest, 2. resting pulse ≥90 beats per minute, 3. resting respiratory rate ≥20 breaths per minute, or 4. oxygen saturation ≤ 93% on room air at sea level. * persons who have not been fully vaccinated against sars-cov-2 and are at high risk of progressing to severe covid-19 illness due to having one of the following underlying conditions and/or sociodemographic risk factors: 1. age ≥ 55 years (with or without comorbidities), 2. body mass index (bmi) ≥30 kg/m² if ≥ 18 years of age or bmi ≥85th percentile for age and gender based on cdc growth charts, 3. chronic kidney disease, 4. diabetes, 5. cardiovascular disease (including congenital heart disease) or hypertension, 6. chronic lung disease (e.g., chronic obstructive pulmonary disease, moderate-to-severe asthma, interstitial lung disease, cystic fibrosis, pulmonary hypertension), 7. sickle cell disease, 8. neurodevelopmental disorders or other conditions that confer medical complexity. * subjects with immunosuppressive disease or receiving immunosuppressive treatment regardless of sars-cov-2 vaccination status. * subjects with active respiratory allergies or subjects expected to require anti-allergy medications during the study period for respiratory allergies. * females of childbearing potential who are either pregnant or sexually active without the use of birth control. * subjects residing in the same household with another subject participating in the study. * treatment with any investigational drug or vaccine therapy within 30 days prior to screening and willing to avoid them during the course of the study. * subjects who have received within the past 90 days or are expected to receive during the study period monoclonal antibody treatment or convalescent covid-19 plasma for covid-19. * receipt of any dose of ntz within seven days prior to screening. * known sensitivity to ntz or any of the excipients comprising the study medication. * subjects unable to swallow oral tablets or capsules. * subjects with known severe heart, lung, neurological or other systemic disease that the investigator believes could preclude safe participation. * subjects likely or expected to require hospitalization unrelated to covid-19 during the study period. * subjects taking medications considered to be major cyp2c8 substrates. * subjects who, in the judgment of the investigator, will be unlikely to comply with the requirements of this protocol including completion of the subject diary.

persons with any clinical sign or symptoms suggestive of moderate or severe systemic illness with covid-19, including the following: shortness of breath at rest, resting pulse ≥90 beats per minute, resting respiratory rate ≥20 breaths per minute, or oxygen saturation ≤ 93% on room air at sea level. persons who have not been fully vaccinated against sars-cov-2 and are at high risk of progressing to severe covid-19 illness due to having one of the following underlying conditions and/or sociodemographic risk factors: age ≥ 55 years (with or without comorbidities), body mass index (bmi) ≥30 kg/m² if ≥ 18 years of age or bmi ≥85th percentile for age and gender based on cdc growth charts, chronic kidney disease, diabetes, cardiovascular disease (including congenital heart disease) or hypertension, chronic lung disease (e.g., chronic obstructive pulmonary disease, moderate-to-severe asthma, interstitial lung disease, cystic fibrosis, pulmonary hypertension), sickle cell disease, neurodevelopmental disorders or other conditions that confer medical complexity. subjects with immunosuppressive disease or receiving immunosuppressive treatment regardless of sars-cov-2 vaccination status. subjects with active respiratory allergies or subjects expected to require anti-allergy medications during the study period for respiratory allergies. females of childbearing potential who are either pregnant or sexually active without the use of birth control. subjects residing in the same household with another subject participating in the study. treatment with any investigational drug or vaccine therapy within 30 days prior to screening and willing to avoid them during the course of the study. subjects who have received within the past 90 days or are expected to receive during the study period monoclonal antibody treatment or convalescent covid-19 plasma for covid-19. receipt of any dose of ntz within seven days prior to screening. known sensitivity to ntz or any of the excipients comprising the study medication. subjects unable to swallow oral tablets or capsules. subjects with known severe heart, lung, neurological or other systemic disease that the investigator believes could preclude safe participation. subjects likely or expected to require hospitalization unrelated to covid-19 during the study period. subjects taking medications considered to be major cyp2c8 substrates. subjects who, in the judgment of the investigator, will be unlikely to comply with the requirements of this protocol including completion of the subject diary.

persons with any clinical sign or symptoms suggestive of moderate or severe systemic illness with covid-19, including the following: shortness of breath at rest, resting pulse ≥90 beats per minute, resting respiratory rate ≥20 breaths per minute, or oxygen saturation ≤ 93% on room air at sea level. persons who have not been fully vaccinated against sars-cov-2 and are at high risk of progressing to severe covid-19 illness due to having one of the following underlying conditions and/or sociodemographic risk factors: age ≥ 55 years (with or without comorbidities), body mass index (bmi) ≥30 kg/m² if ≥ 18 years of age or bmi ≥85th percentile for age and gender based on cdc growth charts, chronic kidney disease, diabetes, cardiovascular disease (including congenital heart disease) or hypertension, chronic lung disease (e.g., chronic obstructive pulmonary disease, moderate-to-severe asthma, interstitial lung disease, cystic fibrosis, pulmonary hypertension), sickle cell disease, neurodevelopmental disorders or other conditions that confer medical complexity. subjects with immunosuppressive disease or receiving immunosuppressive treatment regardless of sars-cov-2 vaccination status. subjects with active respiratory allergies or subjects expected to require anti-allergy medications during the study period for respiratory allergies. females of childbearing potential who are either pregnant or sexually active without the use of birth control. subjects residing in the same household with another subject participating in the study. treatment with any investigational drug or vaccine therapy within 30 days prior to screening and willing to avoid them during the course of the study. subjects who have received within the past 90 days or are expected to receive during the study period monoclonal antibody treatment or convalescent covid-19 plasma for covid-19. receipt of any dose of ntz within seven days prior to screening. known sensitivity to ntz or any of the excipients comprising the study medication. subjects unable to swallow oral tablets or capsules. subjects with known severe heart, lung, neurological or other systemic disease that the investigator believes could preclude safe participation. subjects likely or expected to require hospitalization unrelated to covid-19 during the study period. subjects taking medications considered to be major cyp2c8 substrates. subjects who, in the judgment of the investigator, will be unlikely to comply with the requirements of this protocol including completion of the subject diary.