Antibody responses to the coronavirus can peak three weeks after onset of symptoms, but then begin to decline after as little as two months, researchers at Kings College London found.
The study examined the antibody levels of patients and health-care workers who had tested positive for the virus.
WHO officials warned that studies suggest Covid-19 immunity may wane after a few months.
https://www.cnbc.com/2020/07/14/immunity-to-covid-19-uk-study.html