Perl said she was treated with hydroxychloroquine, an anti-malarial drug, and azithromycin, an antibiotic often referred to as a Z-Pak. She never needed a ventilator, but stayed on oxygen, which she was using anyway for a heart condition. But it’s unclear exactly what ultimately helped her. Several factors might have influenced Boccard’s unlikely success against the virus, including just how much virus Boccard was exposed to at the time of infection, said Dr. Aileen Marty, a professor of infectious diseases at Florida International University. A lighter exposure to the virus could make it easier to beat. Medications she was already...