A new study that analyzed blood donations from December 2019 to early January helped show that the coronavirus infected people in the U.S. earlier than previously thought.

SPRING VALLEY, NY – APRIL 24: A phlebotomist processes specimens of people getting tested for coronavirus antibodies at the Refuah Health Center on April 24, 2020 in Spring Valley, New York. One possible option in treating COVID-19 is giving patients the plasma of those who have already recovered from the disease hoping the blood has the antibodies to cure the virus. Members of the Orthodox Jewish community converged on testing locations to determine of they are candidate to donate plasma. (Photo by Yana Paskova/Getty Images)