* requiring either invasive or non-invasive ventilation including cpap or high flow nasal oxygen at any point after hospital admission and before baseline not related to a pre-existing condition (e.g. obstructive sleep apnoea) * grade ≥ 5 severity on the modified who covid-19 ordinal scale, viz. o2 saturation \< 90% on ≥ 60% inspired oxygen at baseline; non-invasive ventilation; or invasive mechanical ventilation at any point since hospital admission. * in the opinion of the investigator, progression to death is inevitable within the next 24 hours, irrespective of the provision of therapy * known severe allergic reactions to the investigational agents * child pugh b or c grade hepatic dysfunction * use of drugs within the preceding 14 days that are known to interact with any study treatment (fos or rux), as listed in the summary of product characteristics * pregnant or breast feeding * any medical condition or concomitant medication that in the opinion of the investigator would compromise subjects' safety or compliance with study procedures. * any medical condition which in the opinion of the principal investigator would compromise the scientific integrity of the study * pregnant or breast feeding

* requiring either invasive or non-invasive ventilation including cpap or high flow nasal oxygen at any point after hospital admission and before baseline not related to a pre-existing condition (e.g. obstructive sleep apnoea) * grade ≥ 5 severity on the modified who covid-19 ordinal scale, viz. o2 saturation \< 90% on ≥ 60% inspired oxygen at baseline; non-invasive ventilation; or invasive mechanical ventilation at any point since hospital admission. * in the opinion of the investigator, progression to death is inevitable within the next 24 hours, irrespective of the provision of therapy * known severe allergic reactions to the investigational agents * child pugh b or c grade hepatic dysfunction * use of drugs within the preceding 14 days that are known to interact with any study treatment (fos or rux), as listed in the summary of product characteristics * pregnant or breast feeding * any medical condition or concomitant medication that in the opinion of the investigator would compromise subjects' safety or compliance with study procedures. * any medical condition which in the opinion of the principal investigator would compromise the scientific integrity of the study * pregnant or breast feeding

requiring either invasive or non-invasive ventilation including cpap or high flow nasal oxygen at any point after hospital admission and before baseline not related to a pre-existing condition (e.g. obstructive sleep apnoea) grade ≥ 5 severity on the modified who covid-19 ordinal scale, viz. o2 saturation < 90% on ≥ 60% inspired oxygen at baseline; non-invasive ventilation; or invasive mechanical ventilation at any point since hospital admission. in the opinion of the investigator, progression to death is inevitable within the next 24 hours, irrespective of the provision of therapy known severe allergic reactions to the investigational agents child pugh b or c grade hepatic dysfunction use of drugs within the preceding 14 days that are known to interact with any study treatment (fos or rux), as listed in the summary of product characteristics pregnant or breast feeding any medical condition or concomitant medication that in the opinion of the investigator would compromise subjects' safety or compliance with study procedures. any medical condition which in the opinion of the principal investigator would compromise the scientific integrity of the study pregnant or breast feeding

requiring either invasive or non-invasive ventilation including cpap or high flow nasal oxygen at any point after hospital admission and before baseline not related to a pre-existing condition (e.g. obstructive sleep apnoea) grade ≥ 5 severity on the modified who covid-19 ordinal scale, viz. o2 saturation < 90% on ≥ 60% inspired oxygen at baseline; non-invasive ventilation; or invasive mechanical ventilation at any point since hospital admission. in the opinion of the investigator, progression to death is inevitable within the next 24 hours, irrespective of the provision of therapy known severe allergic reactions to the investigational agents child pugh b or c grade hepatic dysfunction use of drugs within the preceding 14 days that are known to interact with any study treatment (fos or rux), as listed in the summary of product characteristics pregnant or breast feeding any medical condition or concomitant medication that in the opinion of the investigator would compromise subjects' safety or compliance with study procedures. any medical condition which in the opinion of the principal investigator would compromise the scientific integrity of the study pregnant or breast feeding

- grade ≥ 5 severity on the modified who covid-19 ordinal scale, viz. o2 saturation < 90% on ≥ 60% inspired oxygen at baseline; non-invasive ventilation; or invasive mechanical ventilation at any point since hospital admission. - in the opinion of the investigator, progression to death is inevitable within the next 24 hours, irrespective of the provision of therapy - known severe allergic reactions to the investigational agents - child pugh b or c grade hepatic dysfunction - use of drugs within the preceding 14 days that are known to interact with any study treatment (fos or rux), as listed in the summary of product characteristics - pregnant or breast feeding - any medical condition or concomitant medication that in the opinion of the investigator would compromise subjects' safety or compliance with study procedures. - any medical condition which in the opinion of the principal investigator would compromise the scientific integrity of the study

- grade ≥ 5 severity on the modified who covid-19 ordinal scale, viz. o2 saturation < 90% on ≥ 60% inspired oxygen at baseline; non-invasive ventilation; or invasive mechanical ventilation at any point since hospital admission. - in the opinion of the investigator, progression to death is inevitable within the next 24 hours, irrespective of the provision of therapy - known severe allergic reactions to the investigational agents - child pugh b or c grade hepatic dysfunction - use of drugs within the preceding 14 days that are known to interact with any study treatment (fos or rux), as listed in the summary of product characteristics - pregnant or breast feeding - any medical condition or concomitant medication that in the opinion of the investigator would compromise subjects' safety or compliance with study procedures. - any medical condition which in the opinion of the principal investigator would compromise the scientific integrity of the study

- requiring either invasive or non-invasive ventilation including cpap or high flow nasal oxygen at any point before baseline - grade greater than or equal to 5 severity on the modified who covid-19 ordinal scale, viz. o2 saturation < 90% on greater than or equal to 60% inspired oxygen at baseline; non-invasive ventilation; or invasive mechanical ventilation - in the opinion of the investigator, progression to death is inevitable within the next 24 hours, irrespective of the provision of therapy - known severe allergic reactions to the investigational agents - child pugh b or c grade hepatic dysfunction - end stage renal failure - use of drugs within the preceding 14 days that are known to interact with any study treatment (fos or rux), as listed in the summary of product characteristics - pregnant or breast feeding - any medical condition or concomitant medication that in the opinion of the investigator would compromise subjects' safety or compliance with study procedures. - any medical condition which in the opinion of the principal investigator would compromise the scientific integrity of the study

- requiring either invasive or non-invasive ventilation including cpap or high flow nasal oxygen at any point before baseline - grade greater than or equal to 5 severity on the modified who covid-19 ordinal scale, viz. o2 saturation < 90% on greater than or equal to 60% inspired oxygen at baseline; non-invasive ventilation; or invasive mechanical ventilation - in the opinion of the investigator, progression to death is inevitable within the next 24 hours, irrespective of the provision of therapy - known severe allergic reactions to the investigational agents - child pugh b or c grade hepatic dysfunction - end stage renal failure - use of drugs within the preceding 14 days that are known to interact with any study treatment (fos or rux), as listed in the summary of product characteristics - pregnant or breast feeding - any medical condition or concomitant medication that in the opinion of the investigator would compromise subjects' safety or compliance with study procedures. - any medical condition which in the opinion of the principal investigator would compromise the scientific integrity of the study