Infections of the coronavirus in the U.S. may be up to 10 times what is currently known, according to Centers for Disease Control and Prevention (CDC) data published in JAMA Internal Medicine.
The estimate is based on detection of antibodies in the population. Testing indicates the number of people with antibodies is between two and 13 times the approximately 3.8 million recorded cases of the virus in the U.S., according to the CDC’s research.
An analysis of blood samples from 10 geographic regions, including Washington state, Utah, New York and South Florida, found that New York City has the highest proportion of antibodies within the population, with 24 percent.
May and June data indicates that 2.8 percent of Missourians have antibodies, while 3.6 percent of Philadelphia residents have them.
Epidemiologists believe 60 percent to 70 percent of the population must contract a virus to achieve so-called herd immunity.
“The study rebukes the idea that current population-wide levels of acquired immunity (so-called herd immunity) will pose any substantial impediment to the continued propagation of [coronavirus] in the US, at least for now,” the JAMA authors wrote in an accompanying editorial.
“Most of us are likely still very vulnerable to this virus and we have a long way to go to control it,” Jennifer Nuzzo, an epidemiologist at the John Hopkins Center for Health Security who was uninvolved in the study, told The Washington Post. “This study should put to bed any further argument that we should allow this virus to rip through our communities in order to achieve herd immunity.”
CDC Director Robert Redfield made similar remarks in late June, telling reporters, "This virus causes so much asymptomatic infection … we probably recognized about 10 percent of the outbreak."