Amid a spike in COVID-19 cases among players, the NFL is now requiring coaches, front-office staff and team personnel to receive vaccine booster shots by Dec. 27.

In a memo sent to teams on Monday and obtained by The Associated Press, the league said: “Given the increased prevalence of the virus in our communities, our experts have recommended that we implement the CDC’s recommendation.”

There is no vaccination mandate for players because discussions with the NFL Players Association are ongoing. The NFL says more than 94% of its players are inoculated. Vaccinated players are tested less frequently and face fewer restrictions under the league’s protocols.

The memo announcing the new policy was issued on the same day that 37 players reportedly tested positive for COVID-19, believed to be a single-day record for the pandemic. The positive cases include Rams All-Pro cornerback Jalen Ramsey, Giants rookie wide receiver Kadarius Toney, Chiefs receiver Josh Gordon and Washington defensive lineman Jonathan Allen.

Seahawks coach Pete Carroll on Monday addressed the possibility of players getting complacent about the virus.

“That’s it. That’s the whole issue worldwide,” Carroll said. “People get fatigued from it. We just can’t. We can’t let that happen. Even though everybody is human and you get worn down by the reminders. It’s stressful when you have to be continually reminded and thoughtful of something that you wouldn’t normally do. It wears on you, and we try to avoid it. We look for ways to get out of it. That’s the conversation we hear all the time, that’s the national clamor.

“It is about being diligent. Diligence comes from the constant reminders and the discipline that it takes to stick with it.”

The league’s booster mandate applies to Tier 1 and Tier 2 employees including coaches, trainers and others who have direct contact with players. 

There are some exceptions to the policy, including for individuals who are not yet eligible for boosters or who had COVID-19 or received monoclonal antibodies within the past 90 days. Anyone who becomes eligible later for boosters must receive the shot within 14 days.

The Centers for Disease Control and Prevention recommends booster shots for adults six months after receiving their second Pfizer or Moderna shot or two months after receiving the lone shot in Johnson & Johnson’s primary series.

In Monday’s memo, the NFL said it recommends that teams provide booster shots to all eligible staff “as soon as possible to ensure that we continue to reduce risk of transmission and allow us to complete the NFL season safely during the pandemic.” The league also said clubs should consider making booster shots available to players’ and staff members’ families and cohabitants.

A staffer with the Washington Football Team has become the first known NFL employee to be infected by the omicron variant, The Washington Post reported Monday. The employee, however, is a Tier 3 staffer who does not work directly with players and is not subject to the mandate.

Unlike last last year, no NFL games have been postponed this season. The league has four more weeks to go in its regular season. The playoffs conclude with Super Bowl LVI on Feb. 13 in Inglewood, California.

The Associated Press contributed to this report.