LOS ANGELES, April 28 (Xinhua) -- More than half of all Americans and about 75 percent of kids had been infected by COVID-19 by the end of February this year, according to a new study on antibodies by the U.S. Centers for Disease Control and Prevention (CDC).
The CDC examined blood samples nationwide for a certain kind of antibodies, called anti-nucleocapsid antibodies, which are produced in response to COVID-19 infection but are not produced in response to COVID-19 vaccines.
