A 25-year-old man in Nevada has been identified as the first person in the U.S. to get COVID-19 twice, according to a study published in the medical journal The Lancet on Monday.
Why it matters: The finding indicates that being infected with the virus "might not guarantee total immunity in all cases," the study's researchers write. It also calls into question the value of any potential source or indicator of immunity — whether that's antibody testing, the use of blood plasma as a treatment, or perhaps even a vaccine, per Axios' Sam Baker.
