A medical worker wearing PPE administers a nasal swab test in New York City. Photo: Alexi Rosenfeld/Getty Images

The number of people infected with COVID-19 in 10 regions analyzed by the Centers for Disease Control and Prevention could be six to 24 times higher than the reported rates, according to data released by the agency Tuesday.

The big picture: The analysis, based on antibody tests, shows that many people who did not exhibit symptoms may have been unknowingly spreading the virus within their communities.

Why it matters: The U.S. has been testing about 700,000 people a day. But the agency's new report shows the testing load is still far from enough given the country's enormous caseload.

Details: The report is the largest of its kind to date, analyzing blood tests between March 23 and May 12 from commercial labs in Connecticut, Louisiana, Minnesota, Missouri, New York City, Philadelphia, San Francisco, South Florida, Utah and western Washington state.

  • In June, the CDC's smaller collection of blood tests from cities and states was one of the agency's first indicators that there were tens of millions more cases than what the country was finding.
  • Worth noting: Some of the data is old, with the most recent tests conducted in May. A lot can change over the course of two months, as STAT News points out.

By the numbers: Some cities where the virus is rampant are closing their testing gaps, while some areas could significantly improve, according to the report.

  • New York City: Actual infections and the reported rate in early May decreased compared to early April. The city is nowhere near achieving herd immunity, according to the CDC.
  • Missouri: The prevalence of infections may be 13 times higher than the reported rate.
  • South Florida: Testing rates increased to 2.9% as of April 24 — up from 1.9% just two weeks earlier.

Between the lines: There are still some parts of the U.S. where the coronavirus still has infected only a small fraction of the population. Parts of Utah, Minneapolis-St.Paul, Philadelphia and San Francisco have exposures ranging from 1%-to-3.6%, according to blood tests.

The bottom line: For most regions, it is likely that there are more than 10 times the number of infections than the number of reported cases.

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