The Centers for Disease Control and Prevention (CDC) and public health labs have tested nearly 4,900 people as of Monday for the novel coronavirus.

CDC Director Robert Redfield told members of the House Appropriations Committee Tuesday that figure doesn't include tests run by commercial labs or hospitals, so the actual number of people in the U.S. who have been tested could be higher.

Lawmakers have been critical of the CDC's slow pace of testing, noting that other countries experiencing outbreaks are far ahead of the U.S. in identifying new cases of COVID-19, the disease caused by the coronavirus.

ADVERTISEMENT

"I am very concerned about our nation’s testing capabilities for coronavirus," Rep. Rosa DeLauro Rosa Luisa DeLauroTrump HHS official faces firestorm after attacks on scientists Ahead of a coronavirus vaccine, Mexico's drug pricing to have far-reaching impacts on Americans Shutdown politics set to collide with coronavirus aid MORE (D-Conn.) told Redfield. "The low number of positive tests in the U.S. is likely a byproduct of under-testing, as opposed to an accurate count of the prevalence of coronavirus in the U.S."

There are 791 confirmed cases of COVID-19 in the U.S., according to a tracker by Johns Hopkins University.

Health officials have acknowledged there are likely undetected cases of the disease in the U.S. due to the slow start in testing caused by a faulty test developed by the CDC that was sent to public health labs.

The CDC and the public health labs it works with throughout the U.S. also have a very small capacity to perform tests.

Commercial labs and hospitals will be testing the majority of possible cases, but those operations are just now starting to pick up.

"The most important point about availability of testing is the CDC's focus was to provide testing for the public health system," Redfield said.

ADVERTISEMENT

Public health labs received 75,000 tests last week. More than 1 million tests were sent to commercial labs and hospitals last week.

Redfield said he wished commercial labs would have prepared for testing weeks ago.

"I can tell you having lived through the last eight weeks I would have loved the private sector to be fully engaged eight weeks ago," he said.

Quest Diagnostics launched its tests Monday while LabCorp did so last Thursday.

The administration has also come under fire for not being able to identify how many tests have been conducted by nonpublic health labs.

"We’re working with the CDC and those partners to get an IT reporting system up and running, hopefully this week, where we would be able to get that data, to keep track of how many we’re testing," Health and Human Services Secretary Alex Azar said Tuesday on CNN.

Experts say that because the U.S. wasn't testing widely for COVID-19 weeks ago, some areas of the country experiencing outbreaks are past the point of containment or trying to stop the outbreak.

Some communities have moved to mitigation, which can involve closing schools and other public places and banning large gatherings, in an effort to slow the outbreak and prevent overwhelming the health care system.

There are 162 cases in Washington state, including 22 deaths. There are also ongoing cases of person-to-person spread in parts of California, Florida and New York.

"I would say in general we're in a containment blended [with] mitigation. And in some areas, we're in high mitigation," Redfield said.