* subject has acute or chronic type(s) of porphyria or a family history of porphyria. * subject has demonstrated previous intolerance of 5-ala and/or sfc by topical or oral administration (except for photosensitivity) * pregnant or nursing women * males and females of reproductive potential who have not agreed to use an adequate method of contraception during the study. * subjects who are unable or unwilling to comply with requirements of the clinical trial. * participation in any other clinical trial of an experimental treatment for covid-19 * subjects who may be excluded at the investigator's discretion

* subject has acute or chronic type(s) of porphyria or a family history of porphyria. * subject has demonstrated previous intolerance of 5-ala and/or sfc by topical or oral administration (except for photosensitivity) * pregnant or nursing women * males and females of reproductive potential who have not agreed to use an adequate method of contraception during the study. * subjects who are unable or unwilling to comply with requirements of the clinical trial. * participation in any other clinical trial of an experimental treatment for covid-19 * subjects who may be excluded at the investigator's discretion

- subject has acute or chronic type(s) of porphyria or a family history of porphyria. - subject has demonstrated previous intolerance of 5-ala and/or sfc by topical or oral administration (except for photosensitivity) - pregnant or nursing women - males and females of reproductive potential who have not agreed to use an adequate method of contraception during the study. - subjects who are unable or unwilling to comply with requirements of the clinical trial. - participation in any other clinical trial of an experimental treatment for covid-19 - subjects who may be excluded at the investigator's discretion

- subject has acute or chronic type(s) of porphyria or a family history of porphyria. - subject has demonstrated previous intolerance of 5-ala and/or sfc by topical or oral administration (except for photosensitivity) - pregnant or nursing women - males and females of reproductive potential who have not agreed to use an adequate method of contraception during the study. - subjects who are unable or unwilling to comply with requirements of the clinical trial. - participation in any other clinical trial of an experimental treatment for covid-19 - subjects who may be excluded at the investigator's discretion