Empty Child Syndrome

The Empty Child "plague" was a technological plague which spread around a part of London in 1941. The Ninth Doctor and Rose Tyler encountered the Empty Child and helped play a part in its cure.

History
When conman Captain Jack Harkness planted a Chula ambulance in 1941 London, the Chula nanogenes, who had never previously encountered humans, infected a dying human boy named Jamie caught in the London Blitz. Assuming that the gas mask he was wearing was part of his face, they "healed" him, and unintentionally created the "Empty Child," a "zombie" based on Jamie's characteristics and injuries at death. Thus, everyone affected by the plague inherited a gas mask in place of their faces, severe head trauma on the left side, partial collapse of the right side of their chest cavity, and a gash on the back of their right hands.

The nanogenes also gave the child the standard abilities of Chula soldiers, specifically super-human strength, telepathic abilities, and the ability to communicate using anything with a speaker grill.

The Empty Child still had a child-like mentality and escaped to search for its mother. In doing so, it contaminated other humans with the nanogenes. Those who were infected did likewise so that the nanogenes spread in a fashion similar to a virus. The child, and all victims of it, were infamous for repeating the phrase, "Are you my Mummy?". At first, people were only infected if touched by someone who was already infected, though the plague soon became airborne.

The Empty Child plague was finally stopped when the Ninth Doctor reunited the Empty Child with his mother and the nanogenes understood, recognising the mother as the superior source, the proper sequence for a human of that era. Jamie was fully restored by the nanogenes and the Doctor sent the reprogrammed nanogenes to the other infected humans. Now knowing what a proper human was supposed to look like, the nanogenes restored the people back to their original selves and repaired all of their injuries and aliments in the process. The Doctor also programmed the nanogenes to shut themselves down once they repaired the damage they created to stop them from being a problem again in the future. (TV: The Empty Child, The Doctor Dances)

Shortly afterwards, Jamie's gasmask was collected and stored in the Leamington Spa Lifeboat Museum. It still contained traces of nanogenes in 2007. (GAME: Security Bot)

Behind the scenes
Victims of the Empty Child "plague" under the name "Gas Mask Zombies" are used as enemies in the Doctor Who: Legacy mobile game.