Reinfection is rare for individuals previously infected with SARS-CoV-2. The CDC advises that individuals who have been infected are typically protected from reinfection for at least 3 months. However, this period is almost certainly a lower bound on the true duration of typical, protective immunity. Recent work [here
] shows that immunity is likely durable for 6 months and more. At present, the duration of immunity is unknown for Covid-19. Other coronaviruses have immunity of variable duration, with some coronaviruses that cause the common cold having relatively short immunity whereas other coronaviruses, such as the virus that caused the 2009 SARS outbreak, resulting in immunity for many years after infection.