Provictus was an advanced strain of Good Thinking, engineered from Invictus by Heights Pharmaceuticals.
Effects
Unlike Invictus, Provictus did not intrinsically affect behaviour nor cause death and could be used as a vaccine against the original strain. It read the infected's mind and uploaded their data to the Data Core, which was also able to insert thoughts. (AUDIO: "Invasion: Kill")
History
Dr Larsen said that the intended use of Provictus was to infiltrate terrorist cells. A minister arranged for an outbreak of Invictus as a way to get the population of Cardiff inoculated with Provictus as a means of surveillance and mind-control.
After Dr Godalming inoculated Cardiff, the minister told her to inoculate the whole of the United Kingdom. However, Jack Harkness activated a trojan horse hidden within his personal data to deactivate both strains of the virus. A real vaccine was created and Heights were defeated, with Jack telling the minister that he would be going to prison. (AUDIO: "Invasion: Kill")