Is it required to take informed consent of a patient for HIV ELISA test of a patient admitted in a ward or should it be done like other tests? I have worked in govt set up and once I did HIV ELISA test it came positive in a patient with lung abscess requiring admission in PICU.

Relatives knew his HIV status but we weren't informed in history. When asked after report whether a patient is taking ART they urged how can we do HIV ELISA on a patient.