In a small group of hemodialysis patients with confirmed SARS-CoV-2 infection, we reported that the presence of anti–SARS-CoV-2 IgG overlaps by several weeks with detectable viral RNA in the upper airways.1 The core message of our communication is that this antibody response, although proof of recent exposure to SARS-CoV-2, should not be interpreted as prima facie evidence of immunity to the virus. Viral load was highest during the first week of illness, suggesting that patients are most infectious during this period.