SpaceX chief Elon Musk may have to steer clear of NASA’s Kennedy Space Center after getting mixed COVID-19 test results on the eve of his company’s second crew launch.

Musk took to Twitter on Friday to say he tested positive for coronavirus, then negative twice, then positive again. He said he wasn’t feeling too well the past few days – sniffles, cough, low fever – but currently had no symptoms.

"So ‘Elon Musk Tests Negative for Covid’ is an equally correct title,” he tweeted.

Musk said his first tests were rapid tests, and he was awaiting the results of lab tests. The 15-minute rapid tests are less sensitive than the lab tests, which take longer to process.

At a news conference, NASA Administrator Jim Bridenstine said he expects SpaceX "to do any contact tracing that is appropriate." He stressed it is NASA policy that anyone testing positive for COVID-19 must immediately quarantine and remain isolated.

Neither NASA nor SpaceX representatives would say where Musk was Friday. His company is based in Southern California, where he makes his home. He was inside Kennedy's Launch Control last May for SpaceX’s first astronaut flight last May.

Four astronauts – three Americans and one Japanese – are scheduled to rocket to the International Space Station on Saturday night.

"NASA and SpaceX are going to work through it together and come to the right conclusion," Bridenstine told reporters. "Our astronauts have been in quarantine for weeks and they should not have had contact with anybody (outside their tested inner circle). They should be in good shape."

Bridenstine said it was too early to know if any changes will be necessary for the final stages of the countdown.

One of the test pilots on SpaceX's first astronaut flight, Doug Hurley, said he's certain Musk will be involved with the launch – regardless of where he is.

"Knowing Elon the way I do, they will figure out a way for him to be very much connected," Hurley told The Associated Press (AP) from Houston.

The upcoming crew flight comes just three months after the end of the test flight with Hurley and Bob Behnken, both NASA astronauts. The four are going up for a full space station stay of five to six months. They will be replaced in the spring by yet another crew launched by SpaceX.

NASA turned over space station ferry trips to SpaceX and Boeing, which has yet to launch anyone, following the retirement of the shuttle fleet in 2011. The space agency is looking to save big by no longer having to buy seats on Russian Soyuz capsules for U.S. astronauts. The last ticket, used by a NASA astronaut launched from Kazakhstan in October, cost $90 million.