A vaccination system for delivering a vaccine substance to avian pullets is provided. Such a system includes a vaccine delivery assembly configured to perform a vaccine delivery procedure for delivering a vaccine substance to the avian pullets. A plurality of positioning devices is provided, with each positioning device receiving an avian pullet for presentation to the vaccine delivery assembly. Each positioning device is transported to individually mate with the vaccine delivery assembly to deliver the vaccine substance during the vaccine delivery procedure. Associated methods, devices, and assemblies are also provided.