A new study estimates that nearly a third of the U.S. population (103 million Americans) may have contracted COVID-19 by the end of 2020, with only a fraction of those cases properly reported in public health reports.
Researchers at Columbia University Mailman School of Public Health found that those with mild or no symptoms were likely to report their infections and aggravated the spread of the virus in a new study, published Thursday in the journal Nature.
“The vast majority of infections were not explained by the number of confirmed cases,” Jeffrey Shaman, a professor of environmental health sciences at Columbia University’s Mailman School of Public Health, said in a press release. “It is these undocumented cases, which are often mild or asymptomatic infections, that allow the virus to spread rapidly to the wider population.”
The rate at which probable cases were confirmed – the “finding rate” – increased from 11% to 25% from March to December as the availability and accuracy of evidence increased.
At the same time, the mortality rate fell from 0.8% to 0.3%.
The study found that parts of the country experienced increased infection rates: more than 60 percent of the population in the Upper Midwest and Mississippi Valley, including North and South Dakota, Minnesota, Wisconsin, and Iowa. , was infected by the end of the year.
The researchers analyzed five major metropolitan areas, in which they found that 52% of residents in Los Angeles, 48% in Chicago, 44% in New York City, 44% in Miami and 27% in Phoenix they had contracted the virus by the end of 2020.
The study found seasonal rises in the virus in each city, with sharp rises in spring and fall / winter in New York and Chicago as it calmed down in the summer. Alternatively, LA and Phoenix suffered summer and fall / winter waves. Miami experienced all three, the student found.
“While the landscape has changed with the availability of vaccines and the spread of new variants, it is important to recognize how dangerous the pandemic was in its first year,” said Sen Pei, PhD, assistant professor of science. environmental health at Columbia University Mailman School of Public Health, in the version.
This week, hospitalizations reached levels not seen since January, and more than 100,000 COVID-19 hospitalizations were reported on Thursday.
The rise comes amid a fourth wave of the virus and its highly contagious Delta variant, which killed 1,456 Americans on Wednesday, according to Johns Hopkins. The maximum daily record of 4,460 was set on January 12th.