Millions of Americans may have contracted the new coronavirus at the start of the pandemic, but most were never diagnosed, a new study suggests.
Researchers from Penn State University discovered that up to 8.7 million people were infected with COVID-19, the disease caused by the virus, in the United States in March.
However, more than three-quarters of them, 80 percent, were never confirmed to have the virus due to limited availability of tests and asymptomatic individuals who never sought medical attention.
The researchers saw an increase in influenza-like illness in the US. USA (Up). In New York (top left), 10% of all flu-like cases cannot be attributed to flu or other seasonal viruses
If only a third of all non-flu cases in the US USA They were really coronaviruses, that would mean that 8.7 million people were infected with the virus. Pictured: Nurses care for a coronavirus patient in the ICU at the Regional Medical Center in San José, California on May 21
For the study, published in the journal Science Translational Medicine, the team analyzed data from people who visited doctors’ offices or clinics with influenza-like illness (ILI).
These patients were never diagnosed with seasonal influenza, coronavirus, or other typical winter viruses.
The researchers saw, in March 2020, an increase in cases with flu-like symptoms such as fever and cough, but that cannot be attributed to the flu.
This was true for several states, including Colorado, Louisiana, Maryland, New Jersey, New York, Oregon, Pennsylvania, and Washington.
New York, for example, saw double the amount of ILI without influenza during the fourth week of March 2020.
Additionally, more than 10 percent of all outpatient visits in the state could not be explained by the flu or other seasonal respiratory viruses.
The team estimated that if only a third of all patients in these states were infected with the virus, the increase in ILI would mean that there were about 8.7 million people in the United States with coronaviruses from March 8-28.
But, at the end of the study period, only about 160,000 cases were confirmed in the United States.
This means that, according to the Penn State model, about 2.6 percent of the total US population. USA I was infected in March, not 0.04 percent.
The researchers say there are several reasons why as many as 80 percent of patients were never diagnosed.
During this time, there was limited availability of tests and a high false negative rate of the kits that were available.
Also, many people were asymptomatic or, if they had symptoms, did not always seek medical attention.
“We found a clear and abnormal increase in outpatients with influenza-like illness (ILI) during the COVID-19 epidemic that correlated with the progression of the epidemic in multiple states in the United States,” the authors wrote.
“The increase in outpatients with ILI without influenza was much greater than the number of confirmed cases in each state, providing evidence of a large number of probable symptomatic cases of COVID-19 that were not detected.”
In the United States, there are currently more than 2.3 million confirmed cases of the virus and more than 120,000 deaths.