Miracle Day

"Miracle Day" was the name originally given to 19/20 March 2011, when every human on Earth simply stopped dying. The name, however, still stuck when the phenomenon lasted for months more. It was caused when the Three Families fed the immortal Jack Harkness' blood into the Blessing, which in turn relayed the template to everyone on the planet in seconds.

History
Without any immediately obvious cause, awareness of the event took time to develop. One of the earliest survivals was Oswald Danes, a convicted prisoner in the United States about to be executed; although his lethal injection was carried out flawlessly on 19 March, the only effect was intense but temporary pain from the drugs. As hours passed, doctors around the planet began to realise that deaths of patients under their care (such as Rex Matheson, who was impaled by a metal pole) had abruptly dropped to zero. Age, disease, trauma, and all other normally fatal conditions continued to hurt and debilitate their victims, but without killing them. The level of damage to the body did not matter. (TV: The New World) Extreme examples include an attempted suicide bomber whose entire body was almost totally burned and pulverised but retained some degree of consciousness even after his head was detached from the rest of his body (TV: The New World) and a CIA agent whose neck was broken, yet she managed to stand and stumble away, her head facing backward (TV: Rendition). News media and the general public also began to realise the change. Eventually, the name of the event emerged on the back of the word "miracle," which began to trend across social networking sites.

The only thing that seemed to permanently kill humans was complete incineration; so long as the bodies remained intact to a certain degree, consciousness and life was still possible to a point, but otherwise human beings would continue to exist despite the impossibility of death or recovery. Even detached body parts would still be animated. (TV: The New World) However it was later discovered that jumping off a tall enough building caused people to be forever unconscious, yet not dead, allowing suicide to exist to a certain degree. (TV: The Middle Men) Also, under Angelo Colasanto's bed was a null point to the miracle, where mortality was possible again, and death existed in that one place. A null field generator could exclude a person from the effects of the miracle. (TV: End of the Road)

Unlike the rest of humanity, Jack Harkness, previously an immortal, became vulnerable to injury and death and also began ageing at a normal rate. (TV: The New World)

Cancer cells, which are normally immortal, also became mortal, effectively curing cancer. (TV: End of the Road, Web of Lies)

Eventually it was revealed that The Three Families fed Captain Jack Harkness's immortal blood into a mysterious tunnel called the Blessing that controlled Earth's morphic field. This caused it to change the morphic field so that everyone became immortal. The Families had the plan to take over the immortal world using their connections once everything stabilized. Miracle Day finally ended when Jack Harkness and Rex Matheson fed Jack's now mortal blood into the Blessing, causing the Miracle to reverse itself with Jack regaining his immortality and everyone else regaining their mortality (Apart from Rex Matheson, who replaced most of his blood with some of Jack Harkness'). As the Miracle ended, everyone who was supposed to die woke up for a moment, before finally passing away. (TV: The Blood Line)

Impact
Without death, the human population began to swell rapidly, increasing pressure on resources and on the species itself. The lack of deaths from any disease and the need to keep treating the sick with new medicines was expected to give viruses and bacteria the chance to evolve into unstoppable "superbugs." It was estimated that within four months, Miracle Day would cause a complete environmental and social collapse. (TV: The New World, Rendition) Beyond medical effects, individuals and societies started to react to Miracle Day in myriad ways:


 * Due to an unexpected legal loophole, Oswald Danes was released from prison. (TV: The New World)
 * Fighting in Somalia ceased, as the combatants could no longer stand to fight enemies that would not die. (TV: The New World)
 * The North Korean regime viewed its population as immortal soldiers and began to mobilise troops along its border with South Korea. (TV: The New World)
 * Tutsi in Rwanda bashed in the heads of Hutu villagers and ran over them with bulldozers. (TV: Rendition)
 * India's Prime Minister called for peace with Pakistan, reasoning that they should all make the best of the single life they now had. (TV: Rendition)
 * Doctor Vera Juarez ordered an immediate and radical change to long-established emergency room triage procedures - treating minor injuries before major ones, in order to free hospital beds for the inevitable increase in patients. (TV: Rendition)
 * Protesters in Egypt rioted, attacking the "Western Miracle". (TV: Dead of Night)
 * Apparent actual deaths were reported but turned out to be hoaxes. (TV: Dead of Night)
 * Candlelight vigils of masked individuals calling themselves the Soulless began, reasoning that eternal life had robbed mankind of their souls. (TV: Dead of Night)
 * The percentage of pregnancies that miscarried due to birth defects no longer did so, while retaining the genetic anomalies, resulting in the potential of babies being born without faces or with exposed brains. (TV: Dead of Night)
 * There were rumours of contraceptives being put into drinking water in China or Japan to control the expanding population growth. (TV: Dead of Night)
 * Police were no longer allowed to accuse people of murder, even in situations of seemingly fatal attempts. (TV: Dead of Night)
 * People were divided into categories; Category 3 was normal with no life threatening injuries, Category 2 was fatal injuries or illness (but still alive and concious due to the miracle), and Category 1 was effectively dead, usually deemed as unconscious and unlikely ever to wake up. (TV: The Categories of Life) In order to deal with criminals, a Category 0 was planned, where they would be "executed" like Category 1s. (TV: End of the Road)
 * Governments were forced to set up "overflow camps" (TV: Escape to LA), in which Category 1 and 2 patients were kept. However, these were, in effect, glorified concentration camps, with Category 1 patients being burned alive. (TV: The Categories of Life)
 * The world economy started to collapse, starting with the loss of the pensions as they were naturally invalid now that people could live significantly past the retirement age. (TV: End of the Road)
 * Some people speculated that the switch from mortal to immortal had rendered cancer cells mortal, allowing people to freely smoke, although they kept this information quiet. (TV: End of the Road)
 * The insurance companies had gone bankrupt. (TV: The Gathering)

Notable survivals
These are notable cases of people surviving due to Miracle Day along with the condition that would have caused their death:
 * Oswald Danes - survived lethal injection (TV: The New World), from which he had recovered from enough to not die when the miracle was reversed, though he committed suicide to kill the families anyway moments later.
 * Rex Matheson - impaled with a pole, stabbed with a pen in the same place twice by Colin Maloney, and later replaced most of his blood with that of Jack Harkness. Survived the miracle and due to the blood transfusion, became immortal in the same manner as Jack Harkness. (TV: The New World, The Middle Men, The Blood Line)
 * CIA Archivist - shot by suicide bomber, close to a huge explosion. Presumably died when the miracle was negated or was sent to the modules. (TV: The New World)
 * Suicide bomber - shot in the neck by Captain Jack, at the centre of an explosion, decapitated by a surgeon. Presumably died when the miracle was negated or was sent to the modules (the latter most likely out of mercy). (TV: The New World)
 * Lyn Peterfield - broken neck though later seen with her head rotated 180 degrees on her body, suggesting internal decapitation. Presumably either died in the modules (though when last seen she did not appear to be category one) or when the miracle was negated. (TV: Rendition)
 * Strangled Woman - was strangled by her husband for a long time. Presumably died in the modules as she appeared to be category one. (TV: Dead of Night)
 * Security man - had a rope tied tightly around the neck, preventing any breathing. Presumably died in the modules. (TV: Escape to LA)
 * The Gentleman - shot multiple times by Rex Matheson. Presumably died in the modules. (TV: Escape to LA)
 * Ellis Hartley Monroe - in a crushed car. Presumably died when the miracle was negated unless her remains were discovered before then. (TV: Escape to LA)
 * Geraint Cooper - three heart attacks that would have presumably been fatal. Died when the miracle was negated. (TV: The Blood Line)
 * Zheng Yibao - jumped off a high building, causing him to be unconscious forever but not "dead". De Facto member of the 45 Club. Presumably died when the miracle was negated or in the modules. (TV: The Middle Men)
 * Colin Maloney - strangled by Esther Drummond, shot twice by Ralph. Presumably died in the modules. (TV: The Middle Men)
 * Armed Guard - shot multiple times by SWAT team officer, shot in the head by Andy Davidson. Presumably died in the modules. (TV: Immortal Sins)
 * Brian Friedkin - at the centre of an explosion. Presumably died when the miracle was negated, or in the modules if any remains were retrieved. (TV: End of the Road)
 * Olivia Colasanto - in the same explosion that impacted Friedken. Presumably died when the miracle was negated, or in the modules if any remains were retrieved. (TV: End of the Road)
 * CIA Agent - close to the explosion mentioned above. Presumably died when the miracle was negated or sent to the modules. (TV: End of the Road)
 * Shawnie Yamaguchi - shot three times by an agent of the Families. Presumably died in the modules. (TV: End of the Road)
 * Soldier - shot many times with a machine gun, close to an explosion. (TV: The Blood Line)
 * Female soldier and several other Argentinian soldiers - in a van blown up by the young male soldier. Presumably died when the miracle was negated. (TV: The Blood Line)
 * Allen Shapiro, Noah Vickers and Sandra Morales - close to a bomb detonated by Charlotte Willis. Presumably died when the miracle was negated. (TV: The Blood Line)
 * Numerous operatives of the Three Families in both Shanghai and Buenos Aires became category ones at the hands of the Torchwood team through shooting or neck-breaking. Presumably died when the miracle was negated. (TV: The Blood Line)
 * Girl - unknown. Died when the miracle was negated. (TV: The Blood Line)
 * Esther Drummond - shot by the Cousin. Died when the miracle was negated. (TV: The Blood Line)

Exceptions

 * Jack Harkness, formerly immortal, was apparently rendered mortal and vulnerable by the Miracle. He nearly died when he was poisoned (TV: Rendition) and shot (TV: End of the Road) but survived when his immortality was reinstated.
 * Angelo Colasanto died of old age when his oxygen mask was removed, as his bed was over a device generating a null field that negated the Miracle. (TV: End of the Road)
 * Only humanity was affected by the Miracle, with no other lifeforms on Earth becoming immortal. Had insects been affected, they would have overrun the world within forty-eight hours. (TV: The New World)
 * Miracle Day appears to have had no effect on Amy Pond and Rory Williams, two companions of the Doctor, who were living in the UK at the time of the Miracle and subsequently travelled to Utah and travelled with the Doctor thereafter. (TV: The Impossible Astronaut; date confirmed in TV: Let's Kill Hitler, et al). 
 * Similarly it is not clear if Craig Owens was impacted either. (TV: Closing Time) Interpretations of exactly when this episode takes place differ.) Likewise Sarah Jane Smith and her companions (Series 5 takes place in the fall of 2011 but no reference is made to Miracle Day).