An assembly for an injection device

An assembly for an injection device for injecting a medicament, the assembly comprising:

• a container containing the medicament and having a cap, the container sealed by a septum;
• a sealing element in contact with an external surface of the cap of the container;
• a needle for piercing the septum;
• and
• a needle hub attached to the needle, wherein the sealing element is disposed between the external surface of the cap of the container and an internal surface of the needle hub,
• wherein the assembly is configured to transition from a first state, in which the needle is held away from the septum and a free end of the needle sits in a cavity sealed by the sealing element, to a second state, in which the needle passes through the septum, and
• wherein a seal between the internal surface of the needle hub and the external surface of the cap is provided by the sealing element when the assembly is in the first state and wherein the seal is maintained throughout transition from the first state to the second state and is maintained when the assembly is in the second state.