Antibodies are detected in the blood of people who have been previously infected with or vaccinated against a virus that causes a disease; they show the body’s efforts (past infection) or preparedness (past infection or vaccination) to fight off a specific virus. Once they are made, antibodies may protect people from getting that infection or getting severely ill for some time afterward. Antibodies, whether from infection or vaccination, wane (or diminish) over time. How quickly antibodies wane is different for each disease and each person.­

SARS-CoV-2, the virus that causes COVID-19, is new and what we know about it has changed rapidly. This information will be updated as more data become available. Until scientists have more data on how long antibodies for against SARS-CoV-2 provide protection against becoming infected with SARS-CoV-2 or severely ill with COVID-19.