Adeno-associated virus is one of the main vectors used in gene therapy. However, its success in humans has been limited owing to the immune response it stimulates. In this paper, the authors show that in non-human primates and mice, the neutralizing antibodies that target the vectors can be adsorbed by empty capsids that are delivered with the vectors, hence improving gene delivery. They also enhanced the safety of this approach by generating an empty capsid mutant that cannot enter a cell. The capsid/vector ratio can be optimized for future delivery.