1. Previous microbiological (based on a positive SARS-CoV-2 NAAT result) diagnosis of COVID-19 2. Administration of immunoglobulins and/or any blood products within the 3 months preceding the planned administration of the study vaccine candidate (with the exception of anti-D immunoglobulin) 3. Previous vaccination with any COVID-19 vaccine (main cohort), prior receipt of one dose of a COVID-19 vaccine is permitted (sub-study) 4. Any confirmed or suspected immunosuppressive or immunodeficient state, chronic administration (defined as more than 14 continuous days) of immunosuppressant medication within the past 3 months, except topical steroids or short-term oral steroids (course lasting =14 days) 5. Any contraindication to the specific vaccine to be administered in the study, according to the Green Book or to the Summary of Product Characteristics for a specific vaccine 6. Current major illness of the mother or conditions of the fetus that, in the investigator’s judgment, will substantially increase the risk associated with the participant’s participation in, and completion of, the study or could preclude the evaluation of the participant’s response, including but not limited to the following: 6.1. Uncontrolled gestational hypertension 6.2. Preeclampsia-eclampsia 6.3. Placental abnormality 6.4. Polyhydramnios or oligohydramnios 6.5. Significant bleeding or blood clotting disorder 6.6. Uncontrolled gestational diabetes 6.7. Any signs of premature labor with the current pregnancy or having ongoing intervention (medical/surgical) in the current pregnancy to prevent preterm birth 6.8. Prior stillbirth or neonatal death, preterm delivery (=34 weeks), or previous infant with a known genetic disorder or major congenital anomaly

1. Previous microbiological (based on a positive SARS-CoV-2 NAAT result) diagnosis of COVID-19 2. Administration of immunoglobulins and/or any blood products within the 3 months preceding the planned administration of the study vaccine candidate (with the exception of anti-D immunoglobulin) 3. Previous vaccination with any COVID-19 vaccine (main cohort), prior receipt of one dose of a COVID-19 vaccine is permitted (sub-study) 4. Any confirmed or suspected immunosuppressive or immunodeficient state, chronic administration (defined as more than 14 continuous days) of immunosuppressant medication within the past 3 months, except topical steroids or short-term oral steroids (course lasting =14 days) 5. Any contraindication to the specific vaccine to be administered in the study, according to the Green Book or to the Summary of Product Characteristics for a specific vaccine 6. Current major illness of the mother or conditions of the fetus that, in the investigator’s judgment, will substantially increase the risk associated with the participant’s participation in, and completion of, the study or could preclude the evaluation of the participant’s response, including but not limited to the following: 6.1. Uncontrolled gestational hypertension 6.2. Preeclampsia-eclampsia 6.3. Placental abnormality 6.4. Polyhydramnios or oligohydramnios 6.5. Significant bleeding or blood clotting disorder 6.6. Uncontrolled gestational diabetes 6.7. Any signs of premature labor with the current pregnancy or having ongoing intervention (medical/surgical) in the current pregnancy to prevent preterm birth 6.8. Prior stillbirth or neonatal death, preterm delivery (=34 weeks), or previous infant with a known genetic disorder or major congenital anomaly