Answer — It may be reassuring to NMOSD patients that many of the variants of concern to date have been isolated from younger, healthy individuals, often with no signs or symptoms of COVID-19 disease. Other variants of the virus have been isolated from persons with severe infections lasting a month—or longer. Most RNA viruses, including the SARS-CoV-2 virus that causes COVID-19, intentionally make mistakes when they replicate their “genetic material” (that is RNA). This RNA replication process is called error-prone proofreading: the virus intentionally makes mistakes in its RNA that are not corrected. This process generates many mutants, a few of which may provide a mutant with a competitive advantage to infect more people, cross over to infect animal reservoirs, etc. The essential point is that the virus does not appear to target immunosuppressed persons—it mutates by design regardless of its host.