A study published yesterday in The Lancet Global Health estimates that about 22% of the world's population is at risk for severe COVID-19 because of underlying illnesses and that 4% could require hospitalization.The group of international researchers modeled risk using prevalence data from the Global Burden of Diseases, Injuries, and Risk Factors Study 2017 and from 2020 United Nations population estimates to determine that 1.7 billion people in 188 countries have at least one underlying disease that puts them at high risk for severe COVID-19 (range, less than 5% of those younger than 20 years to more than 70% of those 70 years and older).If infected, about 349 million people, or about 4% of the world's population, could be at high risk and