Dying Light Wiki

A confidential notice to GRE employees with information on THV.

Tachytransmissive Harran Virus or THV, is a more deadly and more infectious variant of the Harran Virus that escaped from a Level 4 GRE lab in Geneva, Switzerland, in the early 2020s, killing 98% of the global human population and consequently triggering the collapse of civilization, a process known as The Fall. The virus was so contagious and lethal that world governments collapsed within just over two years of its outbreak, eventually leaving the European city of Villedor as the last bastion of mankind.

The virus causes respiratory illness, high fevers and then physical and mental decline followed by a "gruesome death".[1] THV is the virus strain featured in Dying Light 2, as opposed to the original strain in Dying Light.


The virus escaped a Level 4 GRE lab in Geneva, Switzerland, in 2020. The exact circumstances of its leak are not yet known in detail.

The first known cases were recorded in Zurich, Switzerland and Paris, France.[2]

Progression and attempts to contain

Early pandemic (~2021-2022)

On October 20th, 2021, newly installed GRE Chief Physician Dr. Kobayashi Katsumi, recommended immediate action as follows:[2]

  • The immediate closure of all European borders
  • Suspension of all civilian air and rail services

She also recommended that national governments introduce the following policies:[2]

  • Isolate individuals thought to be infected
  • Quarantine anyone in close contact with those thought to be infected
  • Issue shelter-at-home orders immediately
  • Incinerate dead bodies

Dr. Katsumi commented that taking these actions would slow the spread of the virus, giving the GRE time to work on a vaccine; the GRE had already begun working on one with private sector companies.[2]

By December 2021, deaths from THV had occurred in Zurich, Paris and London[1], and media report on the virus and its origins in a GRE lab had begun circulating. Furthermore, around this time, the GRE discovered that THV was even more contagious than previously thought. Antizin was still the only effective agent against its spread, but findings in 20 candidate cities confirmed that, like the original Harran Virus, THV was vulnerable to UV light, destroying the virus itself but not curing infected individuals. Estimates made around this time suggested that over half of the global population would be infected within a few weeks.

In light of this, the GRE recommended moving to stage two of the Protocol and outlawing the following:

  • The operation business not deemed an "essential service"
  • Gatherings of more than four people not sharing the same household
  • Free movement by any civilians who are not first responders or essential workers.

In January 2022. all members of the European Union closed their borders, isolated their cities and invoked martial law. This triggered protests against what many saw as excessive control over the lives of the people, with thousands in attendance.[3]

In June 2022, a mass exodus of hundreds of thousands of people, looking for a safer place to live, began across Europe, paralyzing governments which began quickly shutting their borders.[4]

By this point, the United States government had collapsed along with its power grid and the country was placed under martial law[5]. This situation that aggravated chaos caused by fuel rationing. In Asia, Japan had been "decimated" as a result of a variant of THV. Panic and criticism of the GRE during this period intensified.[4]

Mid pandemic (~2023)

By the beginning of 2023, the infection continued to rise, with the mortality rate in Europe reaching 320,000 deaths per week, up from 45,000. At this point, healthcare systems in Spain and Russia had been overwhelmed. In the latter country, the military had begun a campaign of genocide against those suspected of being infected. It had also become clear to the GRE, specifically to Chief Medical Officer Dr. Katsumi, that the Protocol was failing to combat the pandemic.

The situation prompted Dr. Katsumi to declare, in her report, that "nowhere is safe" with "little hope of survival for most of the world's current population". She also stated that the GRE must shift its focus toward preventing the extinction of humanity as a whole.

This shift in focus from pandemic management to ensuring the survival of mankind was reflected by the founding of the Council of Mankind in Villedor in March 2023 which, in its first session, declared Villedor to be only safe remaining city in Europe. This declaration saw a surge of immigrants head toward the city in search of safety.[4]

The Council comprised representatives from several national governments (the Party of Nations), their combined militaries (referred to simply as the Army) and the GRE. While the Council consisted of international representatives, its jurisdiction seemed to mainly cover Villedor. Its actions were largely centered around logistics, such as securing the supply of food, water and power, and disease prevention, with the erection of the wall around the city, barriers between zones, etc. From its earliest meetings, the subject of the GRE's development of the potentially revolutionary compound THV GenMod, a chemical theorized to destroy degrade infected cells, featured prominently in discussions.

Late pandemic and The Fall (~2024-2026)

By spring 2024, Villedor had become the last major city still standing, with all others having fallen to the virus. As such, it became the destination of hundreds of thousands of refugees from all over the world. Rather than allowing their entry, the military initially kept them outside of the city walls. By August of the same year, immigrants deemed "useful" were allowed to enter the city. This selection process exacerbated outrage and violence that had already begun to grip the city in the form of uncontrolled riots.

Post-Fall Period AKA Modern Dark Ages (2026 and beyond)


THV is comparable to rabies.


After contracting THV, the patient experiences four distinct stages of symptom progression (as stated in the GRE document displayed here):

Stage 1: Flu-like symptoms: severe coughing and respiratory congestion, profuse sweating, dilated pupils, fever, body aches and chills.

Stage 2: Body temperature rises to 43 C; increasing delirium; physical degradation begins in the form of skin lesions.

Stage 3: Physical degradation accelerates, manifesting in muscle spasms and seizures. Subject loses ability so speak.

Stage 4: Turning point after which genetic mutations become irreversible.



The virus has an incredibly short incubation period and degrades the nucleobases of human DNA. It affects the nervous system and motor functions.

Suppressant and monitoring

Antizin and UV light are the only known suppressants of THV. A bracelet, known as a Biomarker, is used to monitor the progression of the virus so that patients can avoid "turning". In Villedor, Biomarkers are considered mandatory and those without them are shunned by society, though no new Biomarkers are being manufactured.

An individual known only as McGregor, still alive post-Fall, claims to have invented the Biomarker, stating that the original was far more "useful", providing the wearer with additional strength at the cost of side effects. According to McGregor, GRE Chief Medical Officer Dr. Kobayashi Katsumi frowned upon this particular version of the Biomarker and confiscated the prototype, locking it in a safe in her office at St Joseph's Hospital.

Infection States