https://www.scientificamerican.com/article/what-immunity-to-covid-19-really-means/

The U.S. Food and Drug Administration recently granted an “emergency use authorization” of a blood test for antibodies against SARS-CoV-2, the novel coronavirus that causes COVID-19. It is the first such test to receive approval for the U.S. market. And it comes at a time when health experts and leaders are embracing immunity as a potential end point to the pandemic. In Colorado, a company that makes a coronavirus antibody test has donated kits to the state’s San Miguel County so that everyone there can be tested if they want to. And in Italy, politicians want to use antibody status to determine which people will get “back to work” passes.

Several ambitious surveys to test for these antibodies have now been launched around the globe. The World Health Organization’s Solidarity II study will pool antibody data from more than half a dozen countries. In the U.S., a collaborative multiyear project aims to provide a picture of nationwide antibody prevalence. Its first phase is already collecting samples from blood donors in six major urban areas, including New York City, Seattle and Minneapolis. And the effort will evolve into three national surveys of donors, supported by the Centers for Disease Control and Prevention and conducted this fall and in the fall of 2021.