Bill Gates slammed coronavirus testing in the US in an interview with CNBC, saying that most tests are a "complete waste" because it takes too long for the results to come back.

Gates, the former CEO and founder of Microsoft, believes that people need to get results back sooner so that they're able to "change their behavior so they're not infecting other people."

"The simplest thing, which has to do with such insanity, is you should not reimburse somebody for getting a test that it takes more than 48 hours to get the result back," Gates said on Tuesday.

"That test is a complete waste. And to all these numbers about how much we test, the majority is just complete waste," he added, calling it "insane" to have to pay for test results that could take more than three days and up to a full week.

The US was slow to roll out testing nationwide in the early stages of the pandemic, and experts say the turnaround times to get results have hampered the country's ability to slow the spread of the virus.

Adm. Brett Giroir, the assistant secretary for health at the US Department of Health and Human Services, agrees with Gates that testing needs to be improved.

"I started out by saying that we are never going to be happy with testing until we get turnaround times within 24 hours, and I would be happy with point-of-care testing everywhere. We are not there yet. We are doing everything we can to do that," Giroir told CNN's Jake Tapper on "State of the Union."

Giroir said that half the testing done in the US is conducted at large commercial labs with the average turnaround for test results being 4.27 days, saying that "we need to continually improve our ecosystem."

Giroir said that Quest and LabCorp have been authorized for pool testing, which will help improve efficiency. Cities where there are outbreaks are also having surge testing added.

The US administered 733,243 tests on July 28, which is nearly triple the amount of tests that were being administered near the end of April, according to data from the Covid Tracking Project.

Gates has donated hundreds of millions of dollars to treatment and vaccine research for Covid-19 through the Bill and Melinda Gates Foundation. (CNN)

Update news