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