A needleless IV injection port assembly includes a spiked body provided with a hollow spike, a female luer component, a flexible and resilient spike boot having a tip and spring portion, a centering member, and a-resilient swabbable septum. The spike boot extends over the spike, the centering member is provided over a portion of the spike and spike boot, and the septum is provided between the centering member and an end of the female luer component. The spiked body and the female luer component are secured together to complete the assembly. The length of the female luer component and/or the length of the spike is chosen so that when a separate male luer is positioned over a protuberance on the septum and pushed into the female luer component, the male luer places pressure upon the septum which thereby urges the septum toward the spike. The pressure on the septum causes the spring portion of the boot to be compressed and the tip portion of the boot to be pierced by the tip of the spike. As the septum is further compressed, the septum extends over the spike, with a pre-slit hole in the septum facilitating the extension thereover, such that a hollow of the spike is in fluid communication with the male luer connector. The injection port causes minimal reflux, and the spike boot and septum provide a swabbable antibacterial double barrier over the spike.