- the participant may not enter the trial if any of the following apply: previous receipt of two or more covid-19 vaccine doses history of anaphylaxis, severe allergic disease or reactions likely to be exacerbated by any component of study vaccines (e.g. hypersensitivity to the active substance or any of the listed ingredients of any study vaccine). this includes latex and polyethylene glycol/macrogol (peg) pregnancy, lactation or willingness/intention to become pregnant within 3 months post boost vaccine malignancy requiring receipt of immunosuppressive chemotherapy or radiotherapy for treatment of solid organ cancer/hematological malignancy within the 6 months prior to enrolment. bleeding disorder (e.g. factor deficiency, coagulopathy or platelet disorder), or prior history of significant bleeding or bruising following intramuscular injections or venipuncture. suspected or known current alcohol or drug dependency. 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. insufficient level of language to undertake all study requirements in opinion of the investigators. known hiv antibody positive.

- the participant may not enter the trial if any of the following apply: previous receipt of two or more covid-19 vaccine doses history of anaphylaxis, severe allergic disease or reactions likely to be exacerbated by any component of study vaccines (e.g. hypersensitivity to the active substance or any of the listed ingredients of any study vaccine). this includes latex and polyethylene glycol/macrogol (peg) pregnancy, lactation or willingness/intention to become pregnant within 3 months post boost vaccine malignancy requiring receipt of immunosuppressive chemotherapy or radiotherapy for treatment of solid organ cancer/hematological malignancy within the 6 months prior to enrolment. bleeding disorder (e.g. factor deficiency, coagulopathy or platelet disorder), or prior history of significant bleeding or bruising following intramuscular injections or venipuncture. suspected or known current alcohol or drug dependency. 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. insufficient level of language to undertake all study requirements in opinion of the investigators. known hiv antibody positive.

- the participant may not enter the trial if any of the following apply: 1. previous receipt of two or more covid-19 vaccine doses 2. history of anaphylaxis, severe allergic disease or reactions likely to be exacerbated by any component of study vaccines (e.g. hypersensitivity to the active substance or any of the listed ingredients of any study vaccine). this includes latex and polyethylene glycol/macrogol (peg) 3. pregnancy, lactation or willingness/intention to become pregnant within 3 months post boost vaccine 4. malignancy requiring receipt of immunosuppressive chemotherapy or radiotherapy for treatment of solid organ cancer/hematological malignancy within the 6 months prior to enrolment. 5. bleeding disorder (e.g. factor deficiency, coagulopathy or platelet disorder), or prior history of significant bleeding or bruising following intramuscular injections or venipuncture. 6. suspected or known current alcohol or drug dependency. 7. 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. 8. insufficient level of language to undertake all study requirements in opinion of the investigators. 9. known hiv antibody positive.

- the participant may not enter the trial if any of the following apply: 1. previous receipt of two or more covid-19 vaccine doses 2. history of anaphylaxis, severe allergic disease or reactions likely to be exacerbated by any component of study vaccines (e.g. hypersensitivity to the active substance or any of the listed ingredients of any study vaccine). this includes latex and polyethylene glycol/macrogol (peg) 3. pregnancy, lactation or willingness/intention to become pregnant within 3 months post boost vaccine 4. malignancy requiring receipt of immunosuppressive chemotherapy or radiotherapy for treatment of solid organ cancer/hematological malignancy within the 6 months prior to enrolment. 5. bleeding disorder (e.g. factor deficiency, coagulopathy or platelet disorder), or prior history of significant bleeding or bruising following intramuscular injections or venipuncture. 6. suspected or known current alcohol or drug dependency. 7. 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. 8. insufficient level of language to undertake all study requirements in opinion of the investigators. 9. known hiv antibody positive.