Marc Lipsitch, a professor of epidemiology at Harvards School of Public Health, on Monday issued a stark warning about the dearth of testing for the coronavirus in the U.S.

In an opinion column for The Washington Post , Lipsitch ripped the feckless federal response in speeding up testing delays, which he said meant most cases here are not being confirmed, even now.

He said the true number of people infected with the virus in the U.S. could be more than 10 times higher than the confirmed figure. As of Tuesday morning, the virus had sickened more than 46,000 nationwide. It had killed 582.

Even though many places are reporting relatively small numbers of confirmed cases, this is not comforting, Lipsitch wrote. In many parts of the country, we are seeing rising numbers of flu-like illnesses that when tested, are not flu, and may well actually be COVID-19 if only we could test them.

He added: If we can scale up testing and reduce case numbers through effective social distancing, we should consider testing very widely and resuming isolation and tracing, which work best in synergy with social distancing.

Check out Lipsitchs full op-ed here.