Parent study - Main cohort: To compare the efficacy of AZD3152 to EVUSHELD and/or placebo in the prevention of symptomatic COVID 19 attributable to matched variants (variants that do not contain the F456L mutation);Parent study-Main cohort: To compare the efficacy of AZD3152 to EVUSHELD and/or placebo in the prevention of symptomatic COVID 19 caused by any SARS-CoV-2 variant;Parent study - Main Cohort: To evaluate the safety of AZD3152 and EVUSHELD and/or placebo;Parent study - Sentinel Safety Cohort: To evaluate the safety of AZD5156;Sub-study: To compare the SARS-CoV-2 nAb responses to a current VOC following AZD3152 administration vs SARS-CoV-2 nAb responses to prior variants following EVUSHELD administration;Sub-study: To evaluate the safety of AZD3152 and EVUSHELD

Parent study - Main cohort: To compare the efficacy of AZD3152 to EVUSHELD and/or placebo in the prevention of symptomatic COVID 19 attributable to matched variants (variants that do not contain the F456L mutation);Parent study-Main cohort: To compare the efficacy of AZD3152 to EVUSHELD and/or placebo in the prevention of symptomatic COVID 19 caused by any SARS-CoV-2 variant;Parent study - Main Cohort: To evaluate the safety of AZD3152 and EVUSHELD and/or placebo;Parent study - Sentinel Safety Cohort: To evaluate the safety of AZD5156;Sub-study: To compare the SARS-CoV-2 nAb responses to a current VOC following AZD3152 administration vs SARS-CoV-2 nAb responses to prior variants following EVUSHELD administration;Sub-study: To evaluate the safety of AZD3152 and EVUSHELD

Parent study - Main cohort: To compare the efficacy of AZD3152 to EVUSHELD and/or placebo in the prevention of symptomatic COVID 19;Parent study - Main Cohort: To evaluate the safety of AZD3152 and EVUSHELD and/or placebo;Parent study - Sentinel Safety Cohort: To evaluate the safety of AZD5156;Sub-study: To compare the SARS-CoV-2 nAb responses to a current VOC following AZD3152 administration vs SARS-CoV-2 nAb responses to prior variants following EVUSHELD administration;Sub-study: To evaluate the safety of AZD3152 and EVUSHELD

Parent study - Main cohort: To compare the efficacy of AZD3152 to EVUSHELD and/or placebo in the prevention of symptomatic COVID 19;Parent study - Main Cohort: To evaluate the safety of AZD3152 and EVUSHELD and/or placebo;Parent study - Sentinel Safety Cohort: To evaluate the safety of AZD5156;Sub-study: To compare the SARS-CoV-2 nAb responses to a current VOC following AZD3152 administration vs SARS-CoV-2 nAb responses to prior variants following EVUSHELD administration;Sub-study: To evaluate the safety of AZD3152 and EVUSHELD

Main Cohort: To compare the nAb responses in serum following AZD3152 and AZD7442 administration to the SARS-CoV-2 Alpha variant in serum;Main Cohort: To evaluate the safety of AZD3152 and AZD7442;Sentinel Safety Cohort: To evaluate the safety of AZD5156

Main Cohort: To compare the nAb responses in serum following AZD3152 and AZD7442 administration to the SARS-CoV-2 Alpha variant in serum;Main Cohort: To evaluate the safety of AZD3152 and AZD7442;Sentinel Safety Cohort: To evaluate the safety of AZD5156

To compare the nAb responses in serum following AZD5156 and AZD7442 administration to the SARS-CoV-2 Alpha variant in serum;To evaluate the safety of AZD5156 and AZD7442

To compare the nAb responses in serum following AZD5156 and AZD7442 administration to the SARS-CoV-2 Alpha variant in serum;To evaluate the safety of AZD5156 and AZD7442

Part A - To compare the nAb responses in serum following AZD5156 and AZD7442 administration to the SARS-CoV-2 Alpha variant in serum;Part A - To evaluate the safety of AZD5156 and AZD7442;Part B - To describe the safety of an open label dose of AZD5156 600 mg IM among participants who received AZD5156 or AZD7442 during Part A Main Cohort

Part A - To compare the nAb responses in serum following AZD5156 and AZD7442 administration to the SARS-CoV-2 Alpha variant in serum;Part A - To evaluate the safety of AZD5156 and AZD7442;Part B - To describe the safety of an open label dose of AZD5156 600 mg IM among participants who received AZD5156 or AZD7442 during Part A Main Cohort