exclusion criteria for the first dose - participation in any other covid-19 prophylactic drug trials during the duration of the study. note: participation in covid-19 treatment trials is allowed in the event of hospitalization due to covid-19. the study team should be informed as soon as possible. - positive hiv antibody testing results. - participation in sars-cov-2 serological surveys where participants are informed of their serostatus during the duration of the study. note: disclosure of serostatus post enrolment may accidentally unblind participants to group allocation. participation in this trial can only be allowed if volunteers are kept blinded to their serology results from local/national serological surveys - planned receipt of any licensed or investigational vaccine, other than the study intervention, within 14 days before and after study vaccination. - prior receipt of an investigational or licensed covid-19 vaccine. - administration of immunoglobulins and/or any blood products within three months prior to the planned administration of the investigational products (ips). - any confirmed or suspected immunosuppressive or immunodeficient state; positive hiv status; asplenia; recurrent severe infections and chronic use (more than 14 days) of immunosuppressant medication within the past 6 months. topical steroids or short-term (course lasting ≤14 days) oral steroids are not exclusion criteria. - history of allergic disease or reactions likely to be exacerbated by any component of recombinant covid-19 vaccine (sf9 cells). - any history of angioedema - pregnancy, lactation, or willingness/intention to become pregnant within 90 days after receiving study vaccine - current diagnosis or treatment of cancer (except basal cell carcinoma of the skin and cervical carcinoma in situ) - history of serious psychiatric condition likely to affect participation in the study - a bleeding disorder (e.g. factor deficiency, coagulopathy, or platelet disorder), or prior history of significant bleeding or bruising following im injections or venipuncture - suspected or known current alcohol or drug dependency - severe and/or uncontrolled cardiovascular disease, respiratory disease, gastrointestinal disease, liver disease, renal disease, an endocrine disorder, and neurological illness (mild/moderate well-controlled comorbidities are allowed) - history of laboratory-confirmed covid-19 - continuous use of anticoagulants, such as coumarins and related anticoagulants (i.e. warfarin) or novel oral anticoagulants (i.e. apixaban, rivaroxaban, dabigatran, and edoxaban) - any other significant disease, disorder, or finding which may significantly increase the risk to the volunteer because of participation in the study, affect the ability of the volunteer to participate in the study, or impair interpretation of the study data. exclusion criteria for the second/third dose in this trial, the second/third dose vaccination may be terminated in some cases. these include systemic allergic reactions, severe hypersensitivity reactions, or intolerable grade 3 or higher adverse reactions after the previous vaccination/placebo. if these reactions occur, the participants should not continue to receive the second/third vaccination.

exclusion criteria for the first dose - participation in any other covid-19 prophylactic drug trials during the duration of the study. note: participation in covid-19 treatment trials is allowed in the event of hospitalization due to covid-19. the study team should be informed as soon as possible. - positive hiv antibody testing results. - participation in sars-cov-2 serological surveys where participants are informed of their serostatus during the duration of the study. note: disclosure of serostatus post enrolment may accidentally unblind participants to group allocation. participation in this trial can only be allowed if volunteers are kept blinded to their serology results from local/national serological surveys - planned receipt of any licensed or investigational vaccine, other than the study intervention, within 14 days before and after study vaccination. - prior receipt of an investigational or licensed covid-19 vaccine. - administration of immunoglobulins and/or any blood products within three months prior to the planned administration of the investigational products (ips). - any confirmed or suspected immunosuppressive or immunodeficient state; positive hiv status; asplenia; recurrent severe infections and chronic use (more than 14 days) of immunosuppressant medication within the past 6 months. topical steroids or short-term (course lasting ≤14 days) oral steroids are not exclusion criteria. - history of allergic disease or reactions likely to be exacerbated by any component of recombinant covid-19 vaccine (sf9 cells). - any history of angioedema - pregnancy, lactation, or willingness/intention to become pregnant within 90 days after receiving study vaccine - current diagnosis or treatment of cancer (except basal cell carcinoma of the skin and cervical carcinoma in situ) - history of serious psychiatric condition likely to affect participation in the study - a bleeding disorder (e.g. factor deficiency, coagulopathy, or platelet disorder), or prior history of significant bleeding or bruising following im injections or venipuncture - suspected or known current alcohol or drug dependency - severe and/or uncontrolled cardiovascular disease, respiratory disease, gastrointestinal disease, liver disease, renal disease, an endocrine disorder, and neurological illness (mild/moderate well-controlled comorbidities are allowed) - history of laboratory-confirmed covid-19 - continuous use of anticoagulants, such as coumarins and related anticoagulants (i.e. warfarin) or novel oral anticoagulants (i.e. apixaban, rivaroxaban, dabigatran, and edoxaban) - any other significant disease, disorder, or finding which may significantly increase the risk to the volunteer because of participation in the study, affect the ability of the volunteer to participate in the study, or impair interpretation of the study data. exclusion criteria for the second/third dose in this trial, the second/third dose vaccination may be terminated in some cases. these include systemic allergic reactions, severe hypersensitivity reactions, or intolerable grade 3 or higher adverse reactions after the previous vaccination/placebo. if these reactions occur, the participants should not continue to receive the second/third vaccination.