* planned receipt of any vaccine other (licensed or investigational) than the study intervention within 30 days before and after each study vaccination. * use of any unproven registered and unregistered treatments for covid-19. * prior receipt of an investigational or licensed vaccine likely to impact on interpretation of the trial data (e.g. adenovirus vectored vaccines, any coronavirus vaccines). * administration of immunoglobulins and/ or any blood products within the three months preceding the planned administration of the vaccine candidate. * hbsag positivity on the screening sample. * grade 2 or higher level of abnormality for fbc, u\&e or lft based on daids grading criteria (version 2.1, july 2017) * history of allergic disease or reactions likely to be exacerbated by any component of the chadox1 ncov-19 vaccine. * any history of hereditary angioedema or idiopathic angioedema. * any history of anaphylaxis in relation to vaccination. * pregnancy, lactation or willingness/intention to become pregnant during the study. * history 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. * bleeding disorder (e.g. factor deficiency, coagulopathy or platelet disorder), or prior history of significant bleeding or bruising following im injections or venipuncture. * any other serious chronic illness requiring hospital specialist supervision. * chronic respiratory diseases, including asthma * chronic cardiovascular disease, gastrointestinal disease, liver disease, renal disease, endocrine disorder and neurological illness * seriously overweight (bmi ≥ 40 kg/m2) * suspected or known current alcohol abuse as defined by an alcohol intake of greater than 42 units every week. * suspected or known injecting drug abuse in the 5 years preceding enrollment. * any clinically significant abnormal finding on screening urinalysis. * any other significant disease, disorder or finding which may significantly increase the risk to the participant because of participation in the study, affect the ability of the participant to participate in the study or impair interpretation of the study data. * history of laboratory confirmed covid-19 illness or known contact with a person that was infected with sars-cov-2. * new onset of fever or a cough or shortness of breath in the 30 days preceding screening and/or enrollment * travel history to any other country with widespread epidemic since january 2020 * in addition to above, group 1 \& 2 participants need to fulfill the following

* planned receipt of any vaccine other (licensed or investigational) than the study intervention within 30 days before and after each study vaccination. * use of any unproven registered and unregistered treatments for covid-19. * prior receipt of an investigational or licensed vaccine likely to impact on interpretation of the trial data (e.g. adenovirus vectored vaccines, any coronavirus vaccines). * administration of immunoglobulins and/ or any blood products within the three months preceding the planned administration of the vaccine candidate. * hbsag positivity on the screening sample. * grade 2 or higher level of abnormality for fbc, u\&e or lft based on daids grading criteria (version 2.1, july 2017) * history of allergic disease or reactions likely to be exacerbated by any component of the chadox1 ncov-19 vaccine. * any history of hereditary angioedema or idiopathic angioedema. * any history of anaphylaxis in relation to vaccination. * pregnancy, lactation or willingness/intention to become pregnant during the study. * history 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. * bleeding disorder (e.g. factor deficiency, coagulopathy or platelet disorder), or prior history of significant bleeding or bruising following im injections or venipuncture. * any other serious chronic illness requiring hospital specialist supervision. * chronic respiratory diseases, including asthma * chronic cardiovascular disease, gastrointestinal disease, liver disease, renal disease, endocrine disorder and neurological illness * seriously overweight (bmi ≥ 40 kg/m2) * suspected or known current alcohol abuse as defined by an alcohol intake of greater than 42 units every week. * suspected or known injecting drug abuse in the 5 years preceding enrollment. * any clinically significant abnormal finding on screening urinalysis. * any other significant disease, disorder or finding which may significantly increase the risk to the participant because of participation in the study, affect the ability of the participant to participate in the study or impair interpretation of the study data. * history of laboratory confirmed covid-19 illness or known contact with a person that was infected with sars-cov-2. * new onset of fever or a cough or shortness of breath in the 30 days preceding screening and/or enrollment * travel history to any other country with widespread epidemic since january 2020 * in addition to above, group 1 \& 2 participants need to fulfill the following

planned receipt of any vaccine other (licensed or investigational) than the study intervention within 30 days before and after each study vaccination. use of any unproven registered and unregistered treatments for covid-19. prior receipt of an investigational or licensed vaccine likely to impact on interpretation of the trial data (e.g. adenovirus vectored vaccines, any coronavirus vaccines). administration of immunoglobulins and/ or any blood products within the three months preceding the planned administration of the vaccine candidate. hbsag positivity on the screening sample. grade 2 or higher level of abnormality for fbc, u&e or lft based on daids grading criteria (version 2.1, july 2017) history of allergic disease or reactions likely to be exacerbated by any component of the chadox1 ncov-19 vaccine. any history of hereditary angioedema or idiopathic angioedema. any history of anaphylaxis in relation to vaccination. pregnancy, lactation or willingness/intention to become pregnant during the study. history 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. bleeding disorder (e.g. factor deficiency, coagulopathy or platelet disorder), or prior history of significant bleeding or bruising following im injections or venipuncture. any other serious chronic illness requiring hospital specialist supervision. chronic respiratory diseases, including asthma chronic cardiovascular disease, gastrointestinal disease, liver disease, renal disease, endocrine disorder and neurological illness seriously overweight (bmi ≥ 40 kg/m2) suspected or known current alcohol abuse as defined by an alcohol intake of greater than 42 units every week. suspected or known injecting drug abuse in the 5 years preceding enrollment. any clinically significant abnormal finding on screening urinalysis. any other significant disease, disorder or finding which may significantly increase the risk to the participant because of participation in the study, affect the ability of the participant to participate in the study or impair interpretation of the study data. history of laboratory confirmed covid-19 illness or known contact with a person that was infected with sars-cov-2. new onset of fever or a cough or shortness of breath in the 30 days preceding screening and/or enrollment travel history to any other country with widespread epidemic since january 2020 in addition to above, group 1 & 2 participants need to fulfill the following

planned receipt of any vaccine other (licensed or investigational) than the study intervention within 30 days before and after each study vaccination. use of any unproven registered and unregistered treatments for covid-19. prior receipt of an investigational or licensed vaccine likely to impact on interpretation of the trial data (e.g. adenovirus vectored vaccines, any coronavirus vaccines). administration of immunoglobulins and/ or any blood products within the three months preceding the planned administration of the vaccine candidate. hbsag positivity on the screening sample. grade 2 or higher level of abnormality for fbc, u&e or lft based on daids grading criteria (version 2.1, july 2017) history of allergic disease or reactions likely to be exacerbated by any component of the chadox1 ncov-19 vaccine. any history of hereditary angioedema or idiopathic angioedema. any history of anaphylaxis in relation to vaccination. pregnancy, lactation or willingness/intention to become pregnant during the study. history 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. bleeding disorder (e.g. factor deficiency, coagulopathy or platelet disorder), or prior history of significant bleeding or bruising following im injections or venipuncture. any other serious chronic illness requiring hospital specialist supervision. chronic respiratory diseases, including asthma chronic cardiovascular disease, gastrointestinal disease, liver disease, renal disease, endocrine disorder and neurological illness seriously overweight (bmi ≥ 40 kg/m2) suspected or known current alcohol abuse as defined by an alcohol intake of greater than 42 units every week. suspected or known injecting drug abuse in the 5 years preceding enrollment. any clinically significant abnormal finding on screening urinalysis. any other significant disease, disorder or finding which may significantly increase the risk to the participant because of participation in the study, affect the ability of the participant to participate in the study or impair interpretation of the study data. history of laboratory confirmed covid-19 illness or known contact with a person that was infected with sars-cov-2. new onset of fever or a cough or shortness of breath in the 30 days preceding screening and/or enrollment travel history to any other country with widespread epidemic since january 2020 in addition to above, group 1 & 2 participants need to fulfill the following

- planned receipt of any vaccine other (licensed or investigational) than the study intervention within 30 days before and after each study vaccination. - use of any unproven registered and unregistered treatments for covid-19. - prior receipt of an investigational or licensed vaccine likely to impact on interpretation of the trial data (e.g. adenovirus vectored vaccines, any coronavirus vaccines). - administration of immunoglobulins and/ or any blood products within the three months preceding the planned administration of the vaccine candidate. - hbsag positivity on the screening sample. - grade 2 or higher level of abnormality for fbc, u&e or lft based on daids grading criteria (version 2.1, july 2017) - history of allergic disease or reactions likely to be exacerbated by any component of the chadox1 ncov-19 vaccine. - any history of hereditary angioedema or idiopathic angioedema. - any history of anaphylaxis in relation to vaccination. - pregnancy, lactation or willingness/intention to become pregnant during the study. - history 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. - bleeding disorder (e.g. factor deficiency, coagulopathy or platelet disorder), or prior history of significant bleeding or bruising following im injections or venipuncture. - any other serious chronic illness requiring hospital specialist supervision. - chronic respiratory diseases, including asthma - chronic cardiovascular disease, gastrointestinal disease, liver disease, renal disease, endocrine disorder and neurological illness - seriously overweight (bmi ≥ 40 kg/m2) - suspected or known current alcohol abuse as defined by an alcohol intake of greater than 42 units every week. - suspected or known injecting drug abuse in the 5 years preceding enrollment. - any clinically significant abnormal finding on screening urinalysis. - any other significant disease, disorder or finding which may significantly increase the risk to the participant because of participation in the study, affect the ability of the participant to participate in the study or impair interpretation of the study data. - history of laboratory confirmed covid-19 illness or known contact with a person that was infected with sars-cov-2. - new onset of fever or a cough or shortness of breath in the 30 days preceding screening and/or enrollment - travel history to any other country with widespread epidemic since january 2020 - in addition to above, group 1 & 2 participants need to fulfill the following exclusion criteria: any confirmed or suspected immunosuppressive or immunodeficient state, including hiv infection; asplenia; recurrent severe infections and chronic use (more than 14 days) immunosuppressant medication within the past 6 months ( topical steroids are allowed). - any confirmed or suspected immunosuppressive or immunodeficient state (except hiv infection for group-3), asplenia, recurrent severe infections and chronic use (more than 14 days) immunosuppressant medication within the past 6 months (topical steroids are allowed).

- planned receipt of any vaccine other (licensed or investigational) than the study intervention within 30 days before and after each study vaccination. - use of any unproven registered and unregistered treatments for covid-19. - prior receipt of an investigational or licensed vaccine likely to impact on interpretation of the trial data (e.g. adenovirus vectored vaccines, any coronavirus vaccines). - administration of immunoglobulins and/ or any blood products within the three months preceding the planned administration of the vaccine candidate. - hbsag positivity on the screening sample. - grade 2 or higher level of abnormality for fbc, u&e or lft based on daids grading criteria (version 2.1, july 2017) - history of allergic disease or reactions likely to be exacerbated by any component of the chadox1 ncov-19 vaccine. - any history of hereditary angioedema or idiopathic angioedema. - any history of anaphylaxis in relation to vaccination. - pregnancy, lactation or willingness/intention to become pregnant during the study. - history 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. - bleeding disorder (e.g. factor deficiency, coagulopathy or platelet disorder), or prior history of significant bleeding or bruising following im injections or venipuncture. - any other serious chronic illness requiring hospital specialist supervision. - chronic respiratory diseases, including asthma - chronic cardiovascular disease, gastrointestinal disease, liver disease, renal disease, endocrine disorder and neurological illness - seriously overweight (bmi ≥ 40 kg/m2) - suspected or known current alcohol abuse as defined by an alcohol intake of greater than 42 units every week. - suspected or known injecting drug abuse in the 5 years preceding enrollment. - any clinically significant abnormal finding on screening urinalysis. - any other significant disease, disorder or finding which may significantly increase the risk to the participant because of participation in the study, affect the ability of the participant to participate in the study or impair interpretation of the study data. - history of laboratory confirmed covid-19 illness or known contact with a person that was infected with sars-cov-2. - new onset of fever or a cough or shortness of breath in the 30 days preceding screening and/or enrollment - travel history to any other country with widespread epidemic since january 2020 - in addition to above, group 1 & 2 participants need to fulfill the following exclusion criteria: any confirmed or suspected immunosuppressive or immunodeficient state, including hiv infection; asplenia; recurrent severe infections and chronic use (more than 14 days) immunosuppressant medication within the past 6 months ( topical steroids are allowed). - any confirmed or suspected immunosuppressive or immunodeficient state (except hiv infection for group-3), asplenia, recurrent severe infections and chronic use (more than 14 days) immunosuppressant medication within the past 6 months (topical steroids are allowed).