1. received 3 doses of covid-19 vaccine 2. received 2 doses of covid-19 less than 6 months prior to the start of the trial 3. currently on immunosuppressive medication or anti-cancer chemotherapy 4. hiv infection 5. congenital immune deficiency syndrome 6. has received immunoglobulin or other blood products in the 3 months prior to vaccination 7. study staff and their relatives 8. have a history of a severe allergic reaction to any covid-19 vaccines or have a medical exception to receiving further covid-19 vaccines

1. received 3 doses of covid-19 vaccine 2. received 2 doses of covid-19 less than 6 months prior to the start of the trial 3. currently on immunosuppressive medication or anti-cancer chemotherapy 4. hiv infection 5. congenital immune deficiency syndrome 6. has received immunoglobulin or other blood products in the 3 months prior to vaccination 7. study staff and their relatives 8. have a history of a severe allergic reaction to any covid-19 vaccines or have a medical exception to receiving further covid-19 vaccines

received 3 doses of covid-19 vaccine received 2 doses of covid-19 less than 6 months prior to the start of the trial currently on immunosuppressive medication or anti-cancer chemotherapy hiv infection congenital immune deficiency syndrome has received immunoglobulin or other blood products in the 3 months prior to vaccination study staff and their relatives have a history of a severe allergic reaction to any covid-19 vaccines or have a medical exception to receiving further covid-19 vaccines

received 3 doses of covid-19 vaccine received 2 doses of covid-19 less than 6 months prior to the start of the trial currently on immunosuppressive medication or anti-cancer chemotherapy hiv infection congenital immune deficiency syndrome has received immunoglobulin or other blood products in the 3 months prior to vaccination study staff and their relatives have a history of a severe allergic reaction to any covid-19 vaccines or have a medical exception to receiving further covid-19 vaccines