Boyle was apparently out promoting his deep space flick SUNSHINE (which we don’t get in the US until later in the year), and told an Irish radio station that he’d like to see the toxic killers invade a nearby European country known for its cuisine, bike race, and general Frenchness. The potential title would be the logical progression: 28 MONTHS LATER (I assume because 28 FORTNIGHTS LATER doesn’t translate globally).
Of course, Boyle could just be twisting our nips with a gag… besides, any possible sequel is really up to Fox Atomic, based on how well the sequel does as it mangles people around the world starting in May.