BEIJING, March 4 (Xinhua) -- The U.S. Centers for Disease Control and Prevention estimates that about 140 million people have been infected with the new coronavirus since the outbreak of the new crown epidemic, based on a nationwide survey.
More than 40% of the population is infected
According to CNN reported on March 1, the CDC cooperates with local governments, academic and commercial institutions in the United States to collect blood samples every two weeks through non-new coronavirus testing channels such as routine physical examinations, from 50 states in the United States, the District of Columbia and Puerto Rico overseas.
Healthcare workers work at a COVID-19 testing center in Los Angeles County, U.S., on Jan. 10. Xinhua News Agency
Based on the positive rate of serum antibodies in the sample, the CDC estimates that as of January 31, 1400.18 million people in the United States had been infected with the new crown virus, accounting for about 43% of the total population.
Geographically, with the exception of Nevada, Utah, Arizona and North Dakota, which are difficult to estimate due to too small sample sizes, Wisconsin had the highest rate of infection among the remaining regions, at about 56.1 percent, and Vermont at the lowest at 17.8 percent.
The CDC previously estimated that about 102.9 million people in the United States had been infected with the new coronavirus as of the end of November last year.
A citizen takes a self-sample at a mobile COVID-19 testing site in Washington, D.C., on Jan. 5. Xinhua News Agency (Photo by Shen Ting)
Far more than the number of confirmed cases
According to previous data released by the US Centers for Disease Control and Prevention, as of January 31, the cumulative number of confirmed COVID-19 cases in the United States was about 74.3 million. CNN believes that the difference between the number of confirmed cases and the estimated number of infections is mainly because most asymptomatic and mildly infected people have not been tested for the new crown virus. In addition, many people have recently tested themselves at home with the help of antigen testing, and the results are often not aggregated into the CDC database.
Kris Olsov, associate professor at johns Hopkins University's Bloomberg School of Public Health, believes that the CDC's survey estimates have certain limitations.
Testing of the samples only detected the presence of antibodies, not antibody levels, making it impossible to determine whether the United States had reached herd immunity levels based on this survey. In addition, fewer survey samples came from people of lower socioeconomic status and less access to health care, so the actual number of COVID-19 infections is likely to be higher. (Wang Yijun)