Infectious bronchitis virus (IBV) is a Coronavirus belonging to the gammacoronaviruses. As it can spread rapidly both within and between groups of chickens, it has a high impact on poultry production worldwide. IBV is an RNA virus that mutates at a relatively high rate. This can pose challenges when making vaccination programmes for poultry flocks. Sjaak de Wit and Robert Jan Molenaar discuss ways to induce cross-protection using existing vaccines.