A new study in Science Translational Medicine claims as many as 8.7 million Americans were infected with COVID-19 in March, but more than 80% of them were never diagnosed.

The estimate comes from a review of cases where patients went to the doctor with influenza-like illnesses that were never diagnosed as coronavirus, influenza or any of the other viruses that usually circulate in winter. Only 100,000 novel coronavirus cases were officially reported during that time period. 

The study can be found at this link.

More information about the study can be found in this report from CNN.