First-line immune defences against COVID-19 are short-lived and may explain reinfection. A new study finds that antibodies produced in the nose decline nine months after COVID-19 infection, while antibodies found in the blood last at least a year. Antibodies in the nasal fluid (known as immunoglobulin A, or IgA) provide first-line defence against COVID-19 by blocking SARS-CoV-2 virus when it first enters the respiratory tract. These antibodies are very effective at preventing the virus from entering cells and causing infection. However, the investigators found that the nasal antibodies were only present in those recently infected and were particularly short-lived against

First-line defences short-lived as seen on The Hippocratic Post.