Every two weeks, the CDC collects thousands of blood tests analyzed by commercial labs for reasons unrelated to COVID-19. Those samples are also tested for coronavirus antibodies. The data is from 72,000 blood samples gathered through Jan. 29, which means the number of Americans infected is likely much higher now. The study counts each person only once and includes only antibodies from natural infection, not from vaccination.
Nevada wasn't included in the estimates, and there was insufficient data for North Dakota, Arizona and Utah.
Five things to know, per the study:
1. Infection rate estimates are much higher for children and younger adults. The study found 58 percent of children age 11 or younger have antibodies from natural infection, along with the same share among ages 12-17.
2. Just under half of adults 49 and younger have been infected. The rate decreases to 37 percent for people 50-64 years and 23 percent among Americans 65 or older.
3. At the end of November — just before omicron began spreading in the U.S. — the study estimated 103 million Americans had been infected. According to that measure, 37 million new people got COVID-19 in the two months ending late January.
4. At least half of the population in 14 states have had COVID-19, with Wisconsin reporting 56 percent of its population at one point infected. The other states with a majority infection rate, in descending order, are Georgia, Iowa, Illinois, Ohio, Wyoming, Texas, Indiana, Mississippi, Nebraska, Michigan, New Jersey, Tennessee and Louisiana.
5. Vermont has the lowest estimated infection rate with 18 percent. The next-lowest states in ascending order are Hawaii, Maine, Oregon, Washington, New Hampshire, Virginia and Massachusetts.