Connector for connecting a medical injection device having a distal tip and a sleeve extending around the tip, the sleeve being provided with an inner threaded portion, to a container closed by a pierceable septum, said connector comprising: - a proximal part configured to sealingly engage the tip of the injection device, the proximal part comprising an outer threaded portion configured to be removably screwed to the inner threaded portion of the sleeve, - a distal part configured to be connected to the container, - a hollow spike extending distally from the proximal part, having an internal volume configured to be in fluidic connection with the injection device, the spike being configured to perforate the pierceable septum of the container when the distal part is connected to the container, the spike comprising an opening in a distal end, said opening being configured to create a fluidic connection between the medical injection device and the container, and - a sealing cap mounted on the hollow spike so as to sealingly enclose at least the opening of the hollow spike, the distal part comprising a skirt extending around the hollow spike, the skirt being adapted to enclose at least the collar of the container when connected to said container, the skirt comprising a flange, the sealing cap comprising a closed distal part, a proximal part provided with an opening, and a hollow body that extends from the opening towards the distal part, the hollow body being configured to sealingly engage the hollow spike, characterized in that the proximal part of the sealing cap is configured to be sealingly and at least partially inserted into a groove provided in the flange so that said proximal part of the sealing cap radially abuts an inner surface of the groove. - a proximal part configured to sealingly engage the tip of the injection device, the proximal part comprising an outer threaded portion configured to be removably screwed to the inner threaded portion of the sleeve, - a distal part configured to be connected to the container, - a hollow spike extending distally from the proximal part, having an internal volume configured to be in fluidic connection with the injection device, the spike being configured to perforate the pierceable septum of the container when the distal part is connected to the container, the spike comprising an opening in a distal end, said opening being configured to create a fluidic connection between the medical injection device and the container, and - a sealing cap mounted on the hollow spike so as to sealingly enclose at least the opening of the hollow spike, the distal part comprising a skirt extending around the hollow spike, the skirt being adapted to enclose at least the collar of the container when connected to said container, the skirt comprising a flange, the sealing cap comprising a closed distal part, a proximal part provided with an opening, and a hollow body that extends from the opening towards the distal part, the hollow body being configured to sealingly engage the hollow spike, characterized in that the proximal part of the sealing cap is configured to be sealingly and at least partially inserted into a groove provided in the flange so that said proximal part of the sealing cap radially abuts an inner surface of the groove.