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."
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.
