This MedRxiv Paper fully titled "Prevalence of IgG antibodies to SARS-CoV-2 in Wuhan–implications for the ability to produce long-lasting protective antibodies against SARS-CoV-2" investigates how long antibodies against SARS-CoV-2 last in the body.

• Found that IgG prevalence increased significantly by age among healthcare workers and general workers, but that otherwise rates were low. Very few healthcare providers had IgG antibodies to SARS-CoV-2, though a significant proportion of them had been infected with the virus. After SARS-CoV-2 infection, people are unlikely to produce long-lasting protective antibodies against this virus.
• Has significant implications for herd immunity, antibody-based therapeutics, public health strategies, and vaccine development.
• Also has findings that refute the possibility of using SARS-CoV anitbody therapies for SARS-CoV-2

https://www.medrxiv.org/content/10.1101/2020.06.13.20130252v1.full.pdf