Actually I just Googled again, and they simply say the precise duration is unknown [1]: > IgG antibodies, including IgG against the S and N proteins, persist f

Actually I just Googled again, and they simply say the precise duration is unknown [1]: > IgG antibodies, including IgG against the S and N proteins, persist for at least several months in most persons, but the precise duration of time that antibodies persist after infection is unknown. [1] https://www.cdc.gov/coronavirus/2019-ncov/lab/resources/antibody-tests-guidelines.html https://www.cdc.gov/coronavirus/2019-ncov/lab/resources/anti...