During an appearance on CNN’s State of the Union Sunday morning, Admiral Brett Giroir, the assistant secretary for health at the Department of Health and Human Services, said the average turnaround time for test results is 4.27 days in the U.S. He emphasized that the country’s testing capacity has increased “140-fold” over the course of the virus outbreak.

“Let me assure you that we are not going to stop our efforts until testing is exactly where we want it to be, with rapid turnaround times,” said Giroir. He estimated about 707,000 tests are currently administered per day nationwide.

Giroir outlined several initiatives that aim to accelerate turnaround, including resources for surge testing to hard-hit U.S. cities and surge care to nursing homes nationwide, as well as pooling authorization for two large laboratories, Quest and LabCorp. “Pooling” allows labs to conduct one diagnostic test for COVID-19 on a group of combined respiratory samples, according to the Centers for Disease Control and Prevention (CDC). The practice is meant to conserve resources and increase efficiency.

More information about a “large investment” will be announced later on Sunday, Giroir added.

“We’re trying to bring [the average turnaround time] down,” he said. “I’m never going to be happy until we have this under control.”

White House Chief of Staff Mark Meadows defended U.S. testing rates during an ABC News This Week interview, which also took place Sunday morning. He said improvement efforts should target high-risk groups, including nursing home residents, students and health care workers. Meadows noted that increasing distribution of rapid response tests, which can provide results in as little as 15 minutes, would be beneficial as well.

“But when we look at the regime that we’ve got, we’re testing more than any other country in the world,” he argued.

U.S. health care providers have administered more than 50 million COVID-19 diagnostic tests throughout the pandemic, with seven-day testing averages increasing consistently since the outbreak began. Data released by The Atlantic’s COVID Tracking Project shows daily testing averages reached nearly 800,000 by Sunday.

But as the country continues to report surging diagnosis numbers, hospitalizations and fatalities related to the novel respiratory illness, many health experts say finding a solution to testing backlogs and extended wait times for results is critical. As of Sunday, nearly 4.2 million people have tested positive for COVID-19 in the U.S. since the beginning of the pandemic, according to Johns Hopkins University’s data. Of those diagnosed, at least 146,500 people have died nationwide.

The Harvard Global Health Institute conducts ongoing research to determine individual states’ diagnostic testing targets, based on respective populations and confirmed case data. The institute’s latest report established testing targets using data released through the third week of June. It suggested only six of all U.S. states—Alaska, Hawaii, Connecticut, Vermont, Montana and West Virginia—met or exceeded necessary testing thresholds.

NPR analyzed the institute’s findings in a report published the following week, which incorporated research from the COVID Tracking Project as well. It established a nationwide target of 4.3 million tests administered per day to suppress further virus transmission, and a target of 1.2 million tests per day to mitigate the outbreak.

Newsweek reached out to Giroir’s office and the White House for additional comments, but did not receive replies in time for publication.