The 28-year-old was presented at Camp Nou on Sunday, after completing his switch from Arsenal for an original €10 million fee, with future incentives for individual and team achievements.
Vermaelen - who signed a five-year deal at the Liga giants - brushed aside concerns over his fitness at a news conference to announce his signing, but it appears he may have to wait before joining his team-mates in training.
"New signing Thomas Vermaelen injured his right hamstring while playing at the World Cup in June," read a statement on Barcelona's website.
"His presence in training sessions will depend on how his recovery progresses.
"Vermaelen was announced as a new Barca signing on Saturday afternoon and was officially presented on Sunday. He has a contract until 2019 and has a buyout clause of €80 million."
Vermaelen spent five years at Arsenal and signed off at the Emirates Stadium by lifting the FA Cup.
Meanwhile, Neymar has rejoined training with the rest of the Barca squad, after exercising alone last week.
The Brazil international sustained a fractured vertebra in his country's quarter-final win over Colombia at the World Cup after a robust challenge from Juan Camilo Zuniga, but he is hoping to be fit for the start of the new La Liga season.
