Lasting Immunity Update
CDC - August 17, 2020

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The US CDC published clarifications on some recent guidance regarding quarantine, isolation, and the possibility of SARS-CoV-2 reinfection. On August 3, the CDC updated its isolation guidance to include new information which indicates that individuals infected with SARS-CoV-2 can “continue to test positive for up to 3 months after diagnosis and not be infectious.” On Friday, the CDC clarified that this does not mean that individuals are immune to reinfection for 3 months. Investigation into lasting immunity and risk of reinfection are ongoing, and while there has not been documented evidence of reinfection within 3 months, the possibility or reinfection during this period has not yet been ruled out. The previous guidance stated that “People who have tested positive for COVID-19 do not need to quarantine or get tested again for up to 3 months as long as they do not develop symptoms again.” Some interpreted this statement as implying a 3-month period of immunity, so the CDC clarified that its intent was to state “that retesting someone in the 3 months following initial infection is not necessary” due to the possibility of continued positive tests, even after an individual has recovered and is no longer infectious. The CDC has included updated language about reinfection for multiple guidance pages, including for quarantine and self-isolation.