The Vikings held their annual training camp night practice Saturday night at their headquarters in Eagan.
Some players, including starting quarterback Kirk Cousins, didn't take part because of COVID-19 protocols.
Vikings coach Mike Zimmer wasn't happy.
"This delta variant is rough," he said prior to the practice session. "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."
Zimmer said his anger is not limited to the players.
"I am disappointed that this happened, I'm frustrated with not just my football players that won't get vaccinated, I'm frustrated with anybody," he said.
Zimmer noted that it could be especially damaging to the team if this sort of thing happened during the regular season, and even worse if players were ruled out of a playoff game because of COVID protocols.