Veteran NFL assistant coach Rick Dennison has left his job with the Minnesota Vikings after refusing to be vaccinated for COVID-19, ESPN reported Friday.

Dennison, 63, had been offensive line coach/run game coordinator for two seasons. He is believed to be the first position coach to leave a team over vaccine regulation.

The NFL is requiring that all Tier 1 staff, which includes coaches, scouts, equipment managers and team executives, be fully vaccinated. Players do not have the same rule, but will be under restrictive COVID-19 protocols if they are unvaccinated.

ESPN said the Vikings promoted Dennison's assistant, Phil Rauscher, to fill the vacated position and added Auburn special-teams analyst Ben Steele to the staff.

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Dennison played nine seasons at linebacker for the Denver Broncos before beginning his coaching career in 1995 as a Broncos offensive analyst. He served as offensive coordinator for the Houston Texans, Buffalo Bills and Broncos, and designed the offence that Peyton Manning led to a victory in Super Bowl 50.

The Vikings report to training camp on Tuesday.