Jake Browning was the only Vikings quarterback available for Saturday's annual night practice at TCO Stadium, after the team's other three quarterbacks were forced to quarantine by the NFL's COVID-19 protocols.

Quarterback Kirk Cousins was deemed a high-risk close contact to an infected player, according to a league source, and that player is reportedly fellow quarterback Kellen Mond. Backup quarterback Nate Stanley has also been quarantined, according to NFL Media. The Vikings announced Saturday that "multiple players" were going to be held out because of COVID protocols.

Coach Mike Zimmer did not confirm which players were out, but did say that Browning was vaccinated and available to practice. League rules don't require vaccinated players to isolate if they're close contacts with an infected person.

Zimmer expressed disappointment Saturday before practice, saying, "it's why people should get vaccinated."

"Quite honestly, after everything we went through last year, I'm not surprised one bit," he said. "I am disappointed that this happened. I'm frustrated, not just with my football players who didn't get vaccinated, but I'm frustrated with everybody [who didn't]. We'll just do the best we can."

If Mond has tested positive and is asymptomatic, he can return as quickly as 48 hours with two negative tests taken a day apart. Cousins being isolated as a close contact indicates he is unvaccinated and subject to a five-day quarantine.

That means Cousins could return Thursday at the earliest. Asked in June about whether he is vaccinated, he said he chooses "to keep my medical history private."

The Vikings' first practice with pads is Monday. After an off-day Sunday, the team is scheduled to practice every day the rest of the week, when Browning may still be one of the only passers available.

"They'll have to go virtual until they're admitted back in the building," Zimmer said of the three quarantined quarterbacks.

The three passers were the only players quarantined Saturday because of COVID protocols. Browning, the third-year undrafted quarterback out of Washington, threw every pass during Saturday night's practice, including a successful hurry-up drill with the starting offense. Afterward, teammates huddled around Browning and doused him in water.

Browning will likely get more work this week in his bid for a backup job.

"Jake's really smart. He's vaccinated," Zimmer said. "That helps to be the backup. So, as we move forward here, he's going to get a ton of reps [Saturday night]. I don't go about saying, 'It's going to go a long way,' because we've still got a lot of camp to go, but we'll see. He's out there. He's available. That's important. It's important to be available when you're playing football, a team sport."

Zimmer has implored Vikings players to get vaccinated since they reported to the team's Eagan headquarters this spring. He declined to say how much of the locker room is vaccinated. He was asked if this could be a wake-up call for unvaccinated players.

"How do you know?" Zimmer said. "Some guys are pretty staunch."

The Vikings have already had to rearrange their coaching staff because of the NFL's COVID protocols about inoculation. Offensive line coach Rick Dennison was reassigned to a senior adviser role because NFL rules require vaccination for all coaches, scouts and equipment managers who interact directly with players.

The league has incentivized getting vaccinated by reducing restrictions for vaccinated players — relaxing rules on social distancing, quarantine requirements, travel and mask wearing.

The NFL announced Thursday that nearly 88% of players have received at least one dose and 19 teams are over a 90% vaccination rate.

"This could definitely happen to any team," defensive end Danielle Hunter said. "It happened to us right now, it just gives us a chance to prepare for what might happen or anything that might happen."

Last season, the Denver Broncos had to start receiver Kendall Hinton at quarterback in Week 12 because the four quarterbacks on the roster were quarantined because of COVID.

"Something like this happens a day before a game that has a chance to get you to the playoffs or something like that," Zimmer said. "This Delta variant is rough. You can see the cases going up every single day now. That's why, for the sake of everybody's health, I think it's important. But some people don't understand, I guess."

Staff writer Ben Goessling contributed reporting.

Correction: Previous versions of this article indicated Mond was vaccinated. Mond's vaccination status has not been confirmed by the Star Tribune.