Researchers found that just 25 percent of nasal swabs from hospitalized patients in April detected low levels of the virus.
The team, from Wayne State University, in Detroit, Michigan, says it believes that as states implemented measures, such as social distancing and face mask mandates, the number of severe cases fell.
A new study from Wayne State University found that 50% of hospitalized coronavirus patients were in the intermediate viral load category compared to 25% of patients each in the high and low groups. Pictured: A nurse cares for a coronavirus COVID-19 patient in the ICU at Regional Medical Center in San Jose, California, May 21
Five weeks later, in June, 70% of patients in the low category in comparison with 20% in the intermediate group and 15% in the high group (above)
A total of 708 hospitalized patients at Detroit Medical Center were examined between the period of April 4 and June 5, 2020.
By comparison, only one-quarter each were classified as high or low.
Lower viral loads corresponded with a low percentage of deaths with 45% of those in the high group dying compared to 14% in the low group (above)
About 20 percent of samples were in the intermediate category and approximately 15 percent were in the high group.
Almost half of patients who were in the high viral group died from COVID-19, the disease caused by the virus.
Comparatively, 32 percent of patients in the intermediate category and 14 percent in the low category passed away.
'A downward trend in the initial [viral load] may reflect a reduction in the severity of the pandemic and trends in the viral load values over time may represent a marker to assess the progress of the pandemic.
'Rapid implementation of social distancing measures, lockdown and widespread use of face masks may have contributed to a decrease in the exposure to the virus.'
The findings were presented at the European Society of Clinical Microbiology and Infectious Diseases' Conference on Coronavirus Disease.