JAMA Intern Med: The largest serological survey in the United States shows that the actual number of people infected should be 6-24 times higher.

!---- Currently, according to real-time data from Johns Hopkins University in the United States, the total number of confirmed cases of new crown pneumonia in the United States is 3.94 millionBut a new study from the U.SCenters for Disease Control and Prevention (CDC) suggests that the total number of actual infections should be six to 24 times higherThe study, conducted by CDC researchers and state health officials, is the largest antibody study of its kindThe findings suggest that even taking into account these hidden cases found in 10 U.Scities, many are far from the antibody prevalence required for mass immunityIn addition, researchers aren't sure how long antibodies can remain in a person after infection, and what this means for immunity to the diseaseThe study was published July 22 in JAMA Internal Medicine, the Journal of Internal Medicine of the American Medical Association"These data continue to show that the number of people infected with the new coronavirus far exceeds the number of reported cases," said Fiona Havers, a CDC researcher who led the studyMany of them may not have any symptoms or are just mild illnesses, and they have no idea they are infected"Researchers are still trying to understand the new coronavirusIn an editorial published in JAMA, the authors note that as many as 40 percent of cases are considered asymptomatic, while symptoms caused by the new coronavirus can be highly variableTo better understand how the new crown outbreak spreads invisibly across the United States, researchers collected blood samples from more than 16,000 peopleThe men were left behind during routine tests (such as cholesterol tests) at the hospital between March and MayThey surveyed 10 major cities in Connecticut, Louisiana, Minnesota, Missouri, New York, Philadelphia, California, Florida, Utah and WashingtonEight of the 10 locations included samples from the second outbreak retrieved later in the spring, tracking the change in antibody-positive rates over timeStudies have shown that there is a certain difference between seropositive rate data in all 10 cities and the number of reported cases, and that the proportion of people carrying antibodies varies from region to regionNew York City, for example, saw its antibody-positive rate jump from 6.9 percent at the end of March to more than 23 percent in May, in line with the rapid increase in cases during that timeThe latter's statistics support an earlier study in the state that tested more than 15,000 people in April and found antibodies in 22.7 percent of the participantsIn New York City, the difference between seropositive rates and reported cases was reported to be 12 times different in the first round of sampling and 10 times lower in early May as testing capacity improvedNew York is the only region with such high seropositive ratesIn other regions, the antibody-positive rate is in the single digitsIn the San Francisco Bay Area, for example, the proportion is 1%, while in other areas it is between 2 and 6 per centAreas with low antibody positive rates sometimes have the greatest differences from case reportsIn Missouri, where the antibody-positive rate remained around 3 percent, the first-round sample reportedly found 24 times more cases than reported, and that number dropped to 13 times when the second round of sampling was conducted in the state at the end of MayTaken together, the results add to an earlier report by CDC Director Robert Redfield that cases are undervalued by as much as 10%They also say the 700,000 tests conducted in the U.Sa day are far from enough to fully control the outbreakThe biggest limitation of the current study is that it relies on old dataBecause these samples were taken in early spring, the true antibody-positive rate and the true count of cases may now be higherFlorida, for example, has seen a large number of cases since then, which are not reflected in the study's dataIn addition, since the samples were collected "in situ," the authors acknowledge in their editorial that the outpatientand inpatients included in the study are likely to be non-representative of the general populationThe team continues to reject the idea that group immunity can soon provide large-scale protection Although researchers speculate that as more and more people recover from the virus, natural group immunity may be developed, the results show that most Americans are still susceptible to new coronal pneumonia Even areas like New York City fall far short of the 60 to 70 percent threshold required for mass immunization to take effect "Most of us may still be susceptible to the new coronavirus, and there's a long way to go to control it," said Jennifer Nuzzo, an epidemiologist at the Johns Hopkins University Center for Health and Safety who was not involved in the study The study will calm any further arguments, such as 'we should allow the virus to invade our communities to achieve mass immunization'