Steven Soderbergh thriller Contagion has topped the US box office over the weekend, early figures have shown.The film, which boasts an all-star cast including Matt Damon, Jude Law and Kate Winslet, brought in $23.1m (£14.5m) in its first three days of release, according to Warner Bros.The film tells the story of a race to contain a lethal virus that is threatening the whole planet.Racial drama The Help took the second spot with Warrior in third.The film, about two brothers who battle in a mixed martial arts tournament – and starring British actor Tom Hardy, pulled in $5.6m (£3.5m).The Help, a surprise hit about racial tensions during the US civil rights era, was last week’s number one film and earned $8.7m (£5.4m), taking its total this summer to more than $137m (£86.3m). – BBC