After a COVID hiatus, it wasn't so easy putting the Doobie Brothers' 50th anniversary tour back together again.

Full band rehearsal seven hours a day for three weeks. Extra rehearsals for vocal harmonies. Not to mention relearning old songs they hadn't performed live in years — or ever. Oh yeah, everyone had to be vaccinated.

And one other thing: Michael McDonald, the voice of some of the Doobies' biggest hits, was touring with them for the first time since 1995.

"His songs bring a whole other feel to the set. It's great to hear him sing. It's just an incredible voice," said Doobie Brothers co-founder Tom Johnston, one of three lead singers in the group headed to the State Fair grandstand Tuesday night. "And his keyboard playing, it's like bringing in the gospel church with pop. Whatever it is that Michael's all about, it's something special."

That means Johnston doesn't have to sing "Takin' It to the Streets" anymore (McDonald penned it) while "What a Fool Believes" and "Minute by Minute" — Doobies hits also sung by McDonald — are back in the set list for the first time in years.

Johnston was pumped up as he spoke a few days ago, following the Doobies' second concert after an 18-month layoff.

"The first night was a feeling-out situation. Last night was the way it was supposed to feel. It was a gas," Johnston said Wednesday from Green Bay, Wis. "We found the original footing, with an expanded set. It encompasses from the very [beginning] of the band to now."

Which is as it should be on a 50th anniversary tour for a biker-bar band from Northern California that blossomed into the good-time hitmakers of "Listen to the Music" and "China Grove." Concert material is drawn from 11 different Doobies albums.

After their pandemic break, the Doobies are on top of COVID protocols. All the musicians and crew are vaccinated. Masks are worn everywhere except onstage. A COVID protocol officer is part of the touring entourage.

"Still, with all of that, I wondered," Johnston said. "Having had it [COVID] once myself, it makes you think about it. It depends on where you're playing. Various areas of the country go up and down as far as the intensity [of coronavirus cases] — and shall I say the 'risk' there is, for lack of a better word."

Johnston, 73, came down with COVID-like symptoms (but no official diagnosis) early last year, curtailing the Doobies' Las Vegas residency after just two performances. He was laid up for a month. He has no lingering effects but plenty of concerns.

"I've seen zero masking," he said of the crowds in Iowa and Wisconsin. "It's just like nothing's going on. With the delta variant, if you have a breakthrough, it's fairly common that you can have long-haul [issues]. We don't talk about that. We just do what we're doing. If they [government officials] don't institute a lockdown again, we'll just keep doing it.

"We're set to play places in the South that are on fire right now. That does scare me a little bit. But it's all been great audiences. It's a balancing act."

Playing in front of crowds keeps the band fueled, Johnston said.

Road warriors despite numerous personnel changes over the years, the Doobies performed in St. Paul in 2019 with Santana and 2018 with Steely Dan. They last played the State Fair in 1997, while McDonald appeared there in 2010 as part of the Dukes of September Rhythm Revue with Boz Scaggs and Donald Fagen.

New album due Oct. 1

The COVID hiatus — and vaccinations — enabled the Doobies to expand a planned four-song EP into a full-length album, "Liberté," due Oct. 1.

In concert, the group is playing two tunes from the new EP — "Better Days" and "Don't You Mess With Me," a brawny number in the Johnston boogie-rock style. "Better Days" and "Cannonball," another selection on the EP, speak to life in the home stretch.

"Those are Pat's tunes," Johnston said of his fellow co-founder, singer-guitarist Patrick Simmons. "I think they're pretty much about his life right now."

For their first studio album in seven years, the Doobies worked with Grammy-winning producer John Shanks, known for projects with Kelly Clarkson, Van Halen and Bon Jovi. With a reputation for guitar-driven pop, Shanks also helped with the songwriting.

McDonald was not involved with the new Doobies album. He still has his solo career, Johnston pointed out. However, McDonald did join the Doobies when they were inducted into the Rock & Roll Hall of Fame in November on the impetus of a deluge of 1970s hits including "Black Water" and "Long Train Runnin'."

"It was kind of a long time coming. We've been eligible since I think '95," Johnston said without any hint of bitterness. "We didn't sit around talking about it a lot. We were busy touring. When it did happen, everybody was thrilled. We had to celebrate it in lockdown."

When an older band gets inducted, inquiring minds, especially younger ones, want to know how they got their moniker. The story goes that several of the band members lived in a house in San Jose, and they needed a name for an upcoming gig. Their next-door neighbor said, "Why don't you call yourself the Doobie Brothers because you're always smoking pot?" Doobie was counterculture slang for a marijuana joint.

So what is the best Doobie Brothers song to smoke a doobie to?

"I have no idea," Johnston said with a chuckle. "None of us smoke weed anymore. I haven't done that since the '70s. It's all about the music, maybe more so now than ever."

Twitter: @JonBream • 612-673-1719

Doobie Brothers

Opening: Dirty Dozen Brass Band

When: 7 p.m. Tue.

Where: State Fair grandstand

Tickets: $50-$65, etix.com