["Neutralizing and binding antibody kinetics of COVID-19 patients during hospital and convalescent phases"](https://www.medrxiv.org/content/10.1101/2020.07.18.20156810v...) - Published July 18 2020
- Based on these half-life data, we estimate that the median times for IgM, IgA and IgG to become seronegative are 4.59 (IQR 4.12-5.03), 7.78 (IQR 6.71-9.16) and 42.72 (IQR 33.75-47.96) months post disease onset.
- This study suggests that SARS-CoV-2 infection induces robust neutralizing and binding antibody responses in patients and that humoral immunity against SARS-CoV-2 acquired by infection may persist for a relatively long time.
["SARS-CoV-2 infection induces robust, neutralizing antibody responses that are stable for at least three months"](https://www.medrxiv.org/content/10.1101/2020.07.14.20151126v...) - July 17, 2020
- Here we report that the vast majority of infected individuals with mild-to-moderate COVID-19 experience robust IgG antibody responses against the viral spike protein, based on a dataset of 19,860 individuals screened at Mount Sinai Health System in New York City.
- We also show that titers are stable for at least a period approximating three months, and that anti-spike binding titers significantly correlate with neutralization of authentic SARS-CoV-2. Our data suggests that more than 90% of seroconverters make detectible neutralizing antibody responses and that these titers are stable for at least the near-term future.
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BTW, there's something called immunological memory, your memory B/T cells persist for decades. So even if you, say, were only fully immune to reinfection for 1 week, you could still get to herd immunity by building up enough immunological memory since the presence of memory B/T cells will reduce transmission. Anyway, fortunately COVID-19 produces immunity of several months at least.