说是曾经感染过。哈佛公共卫生学院的研究

An estimated 94% of people in the U.S. have been infected with the COVID-19 virus at least once, according to according to a new paper from researchers at Harvard’s School of Public Health.https://www.spokesman.com/stories/2022/nov/26/just-1-in-20-people-in-the-us-have-dodged-covid-in/