Harlequins prop Joe Marler and Wasps lock Joe Launchbury have withdrawn from England's Six Nations squad.
Launchbury is out through injury, with a stress fracture to his leg, while Marler has withdrawn for personal reasons.
Bath second row Charlie Ewels and Wasps loose-head Tom West will join up with the squad when they gather on Wednesday.
England open their Six Nations campaign against Scotland on 6 February.
Eddie Jones will retain a 28-player squad throughout the tournament, following an agreement with the clubs and the players' union, "in recognition of the challenges presented by the coronavirus pandemic".
Ewels comes in from England's shadow squad, while West earns his first senior call-up.
The 12-man shadow squad will go through the same Covid testing routine as the main squad to ensure they can move into the England camp quickly and safely if needed.
However, they will continue to train and play for their clubs unless required.
England Six Nations squad
Backs: Elliot Daly, Owen Farrell, George Ford, Ollie Lawrence, Max Malins, Jonny May, Paolo Odogwu, Harry Randall, Dan Robson, Henry Slade, Anthony Watson, Ben Youngs.
Forwards: Luke Cowan-Dickie, Tom Curry, Ben Earl, Ellis Genge, Jamie George, Jonny Hill, Maro Itoje, Charlie Ewels, Courtney Lawes, Tom West, Beno Obano, Will Stuart, Sam Underhill, Billy Vunipola, Harry Williams, Mark Wilson.
Shadow squad
Charlie Atkinson, Ali Crossdale, Tom Dunn, George Furbank, Joe Heyes, Jonathan Joseph, Joe Marchant, George Martin, Alex Mitchell, Jacob Umaga, Jack Willis.
Phone: (800) 737. 6040
Fax: (800) 825 5558
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