The multivector pathogen (also agent or nano-agent) was an anti-Borg biological weapon developed by a Federation/Starfleet think tank that included former Borg drone Seven of Nine. The agent combined a retroviral delivery system for the hormonal formula previously developed by Doctor Beverly Crusher along with an experimental anti-assimilation nanite technology developed by Doctor Jarem Kaz and Commander Data during the Covington crisis, which also delivered a refined version of the Project Endgame virus.