Shea joins Birmingham on loan from Stoke
The American winger has failed to break into the first team at the Britannia Stadium since signing from FC Dallas in January 2013, making just three Premier League appearances for the club.
The 24-year-old spent time on loan at Barnsley last term and Birmingham manager Lee Clark is delighted to have brought in cover for injured trio Lee Novak (knee), Denny Johnstone (thigh) and Olly Lee (hamstring).
"I've been chasing Brek for a while and actually wanted to sign him permanently at the start of the season," Clark told the club's official website. "He impressed me when he played for Barnsley here at St. Andrew's on New Year's Day and, given our recent injuries, it made sense to make this loan move, importantly with no recall clause being something that I have stressed all along."
Shea has made 27 senior appearances for the United States national team, scoring two goals in their successful 2013 CONCACAF Gold Cup campaign.
He will go straight into contention for Saturday's home fixture against Leeds United in the Championship.