Trial to Evaluate the Efficacy and Safety of Nitazoxanide (NTZ) for Pre- and Post Exposure Prophylaxis of COVID-19 and Other Viral Respiratory Illnesses (VRI) in Healthcare Workers and Others at Increased Risk of SARS-CoV-2 Infection

Inclusion Criteria:

1. Males and females at least 18 years of age or of legal consenting age based on local
requirements.

2. Persons at increased risk of contracting COVID-19, including:

1. Healthcare workers with known direct occupational exposure to COVID-19 within 7
days prior to enrollment. A qualifying person (i) provides healthcare to patients
and/or (ii) typically positions themselves within 6 feet of patients ("close
contact") and (iii) is a full- time employee (average of ≥ 24 hours/week) in a
high contact area (Emergency Department, Intensive Care Unit, COVID-specific Care
Unit, Walk-in Clinic, Paramedic/First Responder).

2. Persons participating in social activities without the practice of generally
accepted social distancing practices at least three times per week. Qualifying
activities include the presence of at least 10 people in close (<6 feet)
proximity to each other without masks or other personal protective equipment
(e.g., socializing at bars or community/social centers, in-home social
gatherings, classes or trainings, etc.). These subjects must have engaged in such
activities at least three times in the past 7 days and plan to continue these
activities during the study.

3. Must have a smartphone, tablet, computer, or other qualifying internet- enabled device
and daily internet access.

4. Occupational exposure to a person infected with SAR-CoV-2 within 7 days prior to
enrollment or social interaction as defined in criterion 2(b).

5. Willing and able to provide written informed consent and comply with the requirements
of the protocol, including completion of the subject diary.

Exclusion Criteria:

1. Subjects not at increased risk of contracting SARS-CoV-2 from occupational or social
behaviors.

2. Subjects with known severe heart, lung, neurological or other systemic disease that
the Investigator believes could preclude safe participation.

3. Subjects with a history of COVID-19 or known to have developed anti- SARS-CoV-2
antibodies or received a SARS-CoV-2 vaccine.

4. Subjects who experienced a previous episode of acute upper respiratory tract
infection, otitis, bronchitis or sinusitis or received antibiotics for these
conditions or antiviral therapy for influenza within two weeks prior to and including
study day 1.

5. Subjects residing in the same household with another family member currently
participating in the study.

6. Receipt of any dose of NTZ within 7 days prior to screening.

7. 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.

8. Known sensitivity to NTZ or any of the excipients comprising the study medication.

9. Subjects unable to swallow oral tablets or capsules.

10. Females of childbearing potential who are either pregnant or sexually active without
the use of birth control. Female subjects of child-bearing potential that are sexually
active must have a negative baseline pregnancy test and must agree to continue an
acceptable method of birth control for the duration of the study and for 1 month
post-treatment. A double barrier method, oral birth control pills administered for at
least 2 monthly cycle prior to study drug administration, an (intrauterine device)
IUD, or medroxyprogesterone acetate administered intramuscularly for a minimum of one
month prior to study drug administration are acceptable methods of birth control for
inclusion into the study. Female subjects are considered of childbearing potential
unless they are postmenopausal (absence of menstrual bleeding for 1 year or 6 months
if laboratory confirmation of hormonal status), or have had a hysterectomy, bilateral
tubular ligation or bilateral oophorectomy.

11. Females who are breastfeeding.

12. Subjects with active respiratory allergies or subjects expected to require
anti-allergy medications during the study period for respiratory allergies.

13. Subjects taking medications considered to be major CYP2C8 substrates.

14. 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.