The presence of IgG indicates prior exposure to SARs-CoV-2, a prior infection that may be resolved or is still resolving, and protection against reinfection (“protective immunity”). At this time, we have not established the duration of immunity. However, in previous viral outbreaks of SARS (SARS-CoV), IgG has been shown to provide immunity for up to 2 years. In most other viral diseases, IgG responses measurable by serological testing positively correlate with some level of protective immunity. An animal study of SARS-CoV-2 demonstrated protective immunity after infection. Early human studies demonstrate the development of protective/neutralizing antibody responses in individuals infected with SARS-CoV-2.