Clinical Trial of Efficacy and Safety of Sinovac's Adsorbed COVID-19 (Inactivated) Vaccine in Healthcare Professionals

Inclusion Criteria:

1. Adults 18 years of age or older;

2. Healthcare professionals who work in direct contact care of people with possible or
confirmed COVID-19 cases;

3. Agree with periodic contacts by phone or electronic means, and home visits;

4. Show voluntary intention to participate in the study, documented by the informed
consent form signed by participant.

Exclusion Criteria:

1. For females: Pregnancy (confirmed by positive beta-hCG test), breastfeeding or intent
to engage in sexual relations with reproductive intent without use of birth control
methods in the three months following vaccination;

2. Evidence of uncontrolled neurological, cardiac, pulmonary, hepatic or renal disease,
according to anamnesis or physical examination. Significant changes in treatment or
hospitalizations due to worsening of the condition in the last three months are
indicators of uncontrolled disease;

3. Diseases with impaired immune system including: neoplasms (except basal cell
carcinoma), congenital or acquired immunodeficiencies and autoimmune diseases not
controlled according to anamnesis or physical examination. Significant changes in
treatment or hospitalizations due to worsening of the condition in the last three
months are indicators of uncontrolled disease;

4. Behavioral, cognitive or psychiatric disease that, in the opinion of the principal
investigator or his or her representative physician, affects the participant's ability
to understand and cooperate with all study protocol requirements;

5. Any alcohol or drug abuse over the 12 months prior to enrollment in the study that has
caused medical, professional or family problems, indicated by clinical history;

6. History of severe allergic reactions or anaphylaxis to the study vaccine or to
components thereof;

7. History of asplenia;

8. Participation in another clinical trial with an investigational product in the six
months prior to enrollment in the study or planned participation in another clinical
trial within the two years following enrollment;

9. Previous participation in a study to evaluate a COVID-19 vaccine or prior exposure to
a COVID-19 vaccine;

10. Use of immunosuppressant therapy regimens within the six months prior to enrollment in
the study for planned use within the two years following enrollment. Immunosuppressant
therapy regimens include: antineoplastic chemotherapy, radiation therapy and
immunosuppressants to induce transplant tolerance, among others.

11. Use of immunosuppressive doses of corticosteroids within the three months prior to the
enrollment in the study and planned use of immunosuppressive doses of corticoids
within the three months following enrollment in the study. Immunosuppressive doses of
corticosteroids will be considered the equivalent prednisone 20 mg/day for adults, for
longer than one week. Continued use of topical or nasal corticosteroids is not
considered an immunosuppressant;

12. Received blood products (transfusions or immunoglobulins) within the three months
prior to enrollment in the study, or planned administration of blood products or
immunoglobulins within the two years following enrollment in the study;

13. Suspected or confirmed fever within the 72 hours prior to vaccination or axillary
temperature greater than 37.8 °C* on the day of vaccination (enrollment may be
postponed until participant has gone 72 hours without fever);

14. Possible or confirmed case of COVID-19 on the day of vaccination (vaccination can be
postponed until the participant completes 72 hours without symptoms or the diagnosis
is ruled out);

15. Received live attenuated virus vaccine or inactivated vaccine within the 28 days or 14
days, respectively, prior to enrollment in the study, or immunization planned within
the 28 days after enrollment in the study;

16. History of bleeding disorder (e.g. factor deficiency, coagulopathy or platelet
disorder), or prior history of significant bleeding or bruising following IM
injections or venipuncture

17. Any other condition that, in the opinion of the principal investigator or his/her
representative physician, could put the safety/rights of potential participants at
risk or prevent them from complying with this protocol.