One in every 10 U.S adults who received the COVID-19 vaccine experienced “major” side effects, and over a third (36%) suffered “minor” side effects, according to a national survey conducted this month. Based on a U.S. adult population of 258 million in 2020, the results mean that about 17 million adults who got the COVID-19 vaccine experienced major health effects, and roughly 63 million had minor side effects, said Rasmussen Reports, which conducted the survey.