Nearly three-fifths of Americans had been infected by the COVID-19 virus at least once as of February, according to new estimates from the Centers for Disease Control and Prevention (CDC). The results, which are based on seroprevalence research involving blood samples from all 50 states, indicate that infection prevalence varied widely across age groups: It was about 75 percent for children 11 and younger, 74 percent for 12-to-17-year-olds, 64 percent for 18-to-49-year-olds, 50 percent for 50-to-64-year-olds, and 33 percent for Americans 65 or older.
This study suggests that roughly 192 million Americans had been infected as of February, more than twice the number of cases that had been reported at the time. Based on the number of COVID-19 deaths recorded at the end of February, that estimate implies an overall U.S. infection fatality rate (IFR) of about 0.5 percent, which is substantially lower than the estimates used in early epidemiological models that projected as many as 2.2 million COVID-19 deaths in the United States, more than twice the current total. At the same time, the implied IFR is much higher than the estimates suggested by early seroprevalence studies in California and Florida.
