There were likely up to 17 million undiagnosed cases of COVID-19 in the U.S. through July 2020, based on new research that says the number of COVID-19 cases in the U.S. most likely exceeded the number of reported cases. The National Institutes of Health said Wednesday that for every 1 diagnosed case of COVID-19, there were 4.8 undiagnosed cases during the first six months of the pandemic in the U.S. This is thought to include many of the asymptomatic cases that contributed to the spread of the virus. The results came from a cohort of about 8,000 people who submitted blood samples for antibody analysis as part of the NIH SARS-CoV-2 Seroprevalence Project. The study was published Tuesday in Science Translational Medicine.