Lavarnway served as a designated hitter for the Red Sox for a week in August when David Ortiz was sidelined with bursitis in his right heel. During this stint, Lavarnway will be Boston's third catcher.
Weiland also spent some time with the Sox earlier in the year, making two starts in July. The righty could get a start this weekend against the Rays. He will also spend time as a long man in the bullpen.
For Spears, this marks his first stint in the Major Leagues.
Spears, 26, spent the entire season at Pawtucket, hitting .248 with 19 doubles, two triples, eight homers, 45 RBIs, 49 runs scored and 14 stolen bases. His versatility could be of help.
This season, Spears appeared 37 times at second base, 16 at third, four at short, once at first, 23 in right field and 13 in left.
With Conor Jackson, Josh Reddick and Jed Lowrie all nursing nagging injuries, the timing was just right for Spears to join the team. Reddick, who got hit on the left hand by a pitch Saturday, was able to start in right on Monday. Lowrie, who had some stiffness in his left shoulder, could return by Tuesday. Jackson banged into the wall on Sunday.
"We had talked about bringing him up the other day. Conor's a little beat up," said manager Terry Francona. "Lowrie's OK today, but [Spears] is a guy that impressed everyone at Spring Training with his attitude, his ability to play all over the field, so it's a logical guy to get here to help us."