The San Francisco 49ers' plans have been plunged into chaos after Santa Clara County banned all contact sports for three weeks amid the coronavirus pandemic.

Santa Clara County, home of NFL franchise the 49ers and Levi's Stadium, issued enhanced COVID-19 guidelines for professional, collegiate and youth sports on Saturday.

The stringent new social-distancing measures have left the 49ers in limbo, with Kyle Shanahan's side due to host back-to-back games behind closed doors – the Buffalo Bills on December 7 and Washington Football Team on December 13.

"We are aware of the Santa Clara County Public Health Department's emergency directive," the 49ers said in a statement.

"We are working with the NFL and our partners on operational plans and will share details as they are confirmed."

The Santa Clara County order read: "All recreational activities that involve physical contact or close proximity to persons outside one's household, including all contact sports, will be temporarily prohibited. 

"People can continue to engage in outdoor athletics and recreation where social distancing can be maintained at all times."

The NHL's San Jose Sharks also play home games in Santa Clara County – the start of the 2020-21 season has been delayed until at least January 1.

"[This] will temporarily suspend activities that require direct physical contact or interaction in Santa Clara," Santa Clara County counsel James Williams said.

"So, that means that for those teams, they will not be able to play games or have practices where they have direct contact within the county."

The 49ers – last season's Super Bowl finalists – are bottom of the NFC West with a 4-6 record following three consecutive losses.

San Francisco travel to face NFC West leaders the Los Angeles Rams (7-3) on Sunday.