Federal prosecutors have charged about 20 people in the past two weeks with allegedly engaging in various fraud schemes related to the Covid-19 pandemic that amounted to about $150 million in improper government claims, around $20 million of which have been paid, officials said.

The Justice Department has stepped up efforts to uncover theft from programs that were pumping billions of dollars into the healthcare system after the outbreak of the pandemic in 2020. The new cases are filed in districts around the country, and provide a sweeping look at how some healthcare providers allegedly sought to cheat Medicare and other programs by bundling charges for unnecessary services—or those that weren’t ever provided—with the delivery of relatively inexpensive Covid-19 tests.