* history of covid-19 vaccination. * history of serious vaccine allergy. * pregnancy1 * have received an experimental agent within 30 days prior to the study vaccination or expect to receive another experimental agent during the trial reporting period. * any medical, social or mental condition which, in the opinion of the investigator, would be detrimental to the subjects or the study.

* history of covid-19 vaccination. * history of serious vaccine allergy. * pregnancy1 * have received an experimental agent within 30 days prior to the study vaccination or expect to receive another experimental agent during the trial reporting period. * any medical, social or mental condition which, in the opinion of the investigator, would be detrimental to the subjects or the study.

history of covid-19 vaccination. history of serious vaccine allergy. pregnancy1 have received an experimental agent within 30 days prior to the study vaccination or expect to receive another experimental agent during the trial reporting period. any medical, social or mental condition which, in the opinion of the investigator, would be detrimental to the subjects or the study.

history of covid-19 vaccination. history of serious vaccine allergy. pregnancy1 have received an experimental agent within 30 days prior to the study vaccination or expect to receive another experimental agent during the trial reporting period. any medical, social or mental condition which, in the opinion of the investigator, would be detrimental to the subjects or the study.

have a history of severe systemic reactions (anaphylaxis, breathing difficulties, severe rash) following previous immunization with licensed or unlicensed vaccines. have a history of abnormal blood clotting or thrombocytopenia have previously received a covid-19 vaccine have received an experimental agent within 30 days prior to the study vaccination or expect to receive another experimental agent during the trial reporting period. any other serious medical, social or mental condition which, in the opinion of the investigator, would be detrimental to the subjects or the study.

have a history of severe systemic reactions (anaphylaxis, breathing difficulties, severe rash) following previous immunization with licensed or unlicensed vaccines. have a history of abnormal blood clotting or thrombocytopenia have previously received a covid-19 vaccine have received an experimental agent within 30 days prior to the study vaccination or expect to receive another experimental agent during the trial reporting period. any other serious medical, social or mental condition which, in the opinion of the investigator, would be detrimental to the subjects or the study.