What is the purpose of COVID-19 antibody testing?

On an individual level, an antibody test looks for antibodies in the blood. Your immune system makes antibody proteins to help fight infections. If you were exposed to COVID-19, an antibody test will show whether or not you’ve developed antibodies against SARS-CoV-2, the virus that causes COVID-19. An antibody test cannot tell you whether you have a current COVID-19 infection. 

On a population level, antibody testing can give researchers a sense of how many people have been exposed to and infected by COVID-19. In the future, antibody testing may show whether someone has immunity against COVID-19, meaning that they cannot get infected again. If antibodies make people immune to COVID-19, it can help inform leaders and public health officials about whether the population has reached herd immunity. Herd immunity is when a large percentage of a population has become immune to COVID-19, which can protect those people who are not immune.