Sens. Elizabeth Warren, D-Mass., and Tina Smith, D-Minn., have informed the secretary of Health and Human Services they have discovered “significant gaps in COVID-19 testing capacity.”

In a letter this week to HHS chief Alex Azar, Warren and Smith said they made the discovery after contacting five of the worlds largest Covid testing labs: Quest, BioReference, ARUP Labs, LabCorp., and Mayo Clinic.

They said the labs informed them that they experienced a “large spike in COVID-19 diagnostic testing needs” during the summer surge. The letter said the labs are also developing additional testing capacities but are still short on supplies and are experiencing “confusion about payment and reimbursement for COVID-19 diagnostic testing as a result of Congressional and Administration inaction.”