Giants broadcaster Jon Miller and his wife, Janine, got tested for the coronavirus and are quarantining themselves as they await the results.

In a Wednesday morning radio interview on KNBR, Miller said his son and son’s fiancee tested positive for the coronavirus after returning from Europe, where they were engaged.

“They’re young. They’re healthy. You feel bad for them,” Miller said. “They’re just so sick. Anybody who’s been exposed to it, and you read about it, it’s a horrible thing. It’s painful and just so relentless. It never goes away, it seems like.

“They’ve been working with it for what, 10, 12 days now. They said it’s getting a little bit better, and what not. That’s all we can do is what they’ve asked us to do, which is stay away from other people and try to discontinue the spread of it.”

In an interview with The Chronicle, Miller said on March 12, the day Major League Baseball canceled spring training, he and his wife picked up their son and his fiancee from the Phoenix airport and drove them to where they live in Tucson.

The young couple hadn’t experienced symptoms until three days later and weren’t able to get tested until Saturday. They received the test results Monday.

Back on March 12, while symptom-free, they still were cautious with Jon and Janine, telling them not to hug them or touch their luggage just in case they had contracted the coronavirus in Europe.

The next day, Jon and Janine had a scheduled flight back to the Bay Area, but their kids, in a family conference call on Zoom, urged them not to fly.

“They wanted us to do the self-isolating thing right away,” Miller said on KNBR. “So they convinced us, as good citizens, that’s what we needed to do.”

Miller’s last Giants broadcast was March 10. The team played March 11 in Surprise, Ariz., and had been scheduled to be off March 12, the day MLB shut down.

Instead of flying home, Jon and Janine drove. In fact, they had been considering purchasing a new car anyway, so they bought one in Arizona, replacing a 12-year-old Toyota Prius with a 2020 version.

“I said, well how about this? We’ll buy that car she’s wanted for two years. We’ll give the old one to one of our daughters who needs a car, and we’ll drive home,” Miller said. “We’ll self-isolate in our brand-new car. So that’s what we did. We’ve been in lockdown ever since.

“I will say we try to get out and take a walk, self-distancing and isolating. We have had no symptoms of anything, I’m happy to say, even though our son has been sick this whole time.”

Jon and Janine got tested Friday.

“Again, you can have it and feel great, which we do,” Miller said. “We feel fantastic. It’s almost impossible to believe you can spread it, but that’s an actual fact. We don’t want to spread it.”

Miller posted on his Instagram account a selfie with Janine, both wearing masks (given to them by doctors) with the sunset behind them.

In closing the KNBR interview, Miller said, “This is a difficult time, and we hope you and yours are safe and secure in your lockdown and self-isolation situation and we all get together sooner rather than later at 24 Willie Mays Plaza.”

John Shea covers the Giants for The San Francisco Chronicle. Email: jshea@sfchronicle.com Twitter: @JohnSheaHey