Exvid-76

The Extraterrestrial virus disease 2076 (Exvid-76) is an infectious disease caused by a newly discovered virus type affecting production of human gametes and thereby the reproductive system. It was first identified in June 2076 in relatives of astronauts returning from early interstellar missions. While not immediately fatal, within two years the situation had developed into a pandemic threatening humankind's existence by causing widespread sterility.

At the turn of the 22nd century about 80% of Earth's population was affected by Exvid-76, causing the pandemic to be classified as an imminent Extinction Event.

Treatment
Between 2109 and 2113 a treatment in the form of a gene therapy was under development by the HGPP and could be presented by 2113. It is derived from the hugely adaptive gametes found in higher lifeforms on the exoplanet Keto. As a consequence, the altered human genetic code enables human cross-species fertilization. In addition, a side effect is a strengthened immune system and increased resilience against cellular damage, effectively increasing a normal lifespan considerably.

The genetic treatment was acquired by inducing several generations of cross-species pregnancies. In each generation of offspring, the resulting creature inherits more and more human genetic material while retaining the alien code. At a certain point down the genetic line the portion of the genetic code that is responsible for the production of highly adaptive gametes has mutated far enough for it to be inserted into the genetic makeup of a 100% human without being rejected.