• Males or females at least 18 years of age.

• Tested positive for HIV by either blood antigen/antibody combination HIV-1/2 immunoassay, HIV-1/HIV-2 antibody differentiation immunoassay, or nucleic acid tests (e.g., HIV ribonucleic acid \[RNA\] polymerase chain reaction \[PCR\]). Participants who are newly diagnosed with HIV infection by an antigen/antibody combination HIV-1/2 immunoassay are allowed to be included in the study, but the infection should be subsequently confirmed by an HIV-1/HIV-2 antibody differentiation immunoassay or nucleic acid tests.

• Diagnosed with definitive, presumptive, or clinically suspected PCP prior to randomisation.

• Willing and able to provide written informed consent. If the participant is unable to provide consent, a legally acceptable representative (i.e., acceptable to ICH and local law, as applicable) must provide informed consent on the participant's behalf.

• Participants of childbearing potential (all biologically female participants between 18 years and \<2 years post-menopausal unless surgically sterile) must agree to use a highly effective contraceptive measure during the study period (from enrolment) and for at least 30 days after the last dose of rezafungin.

• Biologically male participants who are not vasectomised must agree to the following requirements during the study period (from enrolment) and for at least 120 days after the last dose of rezafungin:

‣ Refrain from donating sperm PLUS, either

⁃ Abstain from sexual intercourse with a female of childbearing potential as their preferred and usual lifestyle OR

⁃ Use barrier contraception (i.e., male condom with or without spermicide) when having sexual intercourse with a female of childbearing potential who is not currently pregnant.