The virus raged on for some time, until Mystique, in an effort to make the world safe for mutants, modified the virus to affect only humans. When Moira found out about the virus, she finally grasped what the key to the cure was. Unfortunately, she was mortally wounded during Mystique's attack on Muir Island and did not live to complete the cure. Professor X did manage to telepathically retrieve the critical information before Moira died, and Beast was able to synthesize the cure a few weeks later.

However, the X-Men soon realized that cure was as deadly as the Virus, at least to the person who would host the cure and release it into the atmosphere. They vowed to keep working until a safer cure could be found. Colossus, whose little sister Illyana had succumbed to the Virus months before, could not abide that decision and injected himself with the cure, sacrificing his life to save the world from the disease.

The following mutants are known to have died from the Legacy Virus:
Aminedi (Iraqi agent), Burke, Infectia, Gordon Lefferts (Sinister's aide), Magik, Mastermind, Multiple Man (one dupe), Nicodemus, Revanche.

Absalom was infected by the virus, but was killed by Selene. Psynapse was actually killed by his teammates due to his infection, which made him "unfit."

The following were infected with the virus in varying degrees:
Abyss, Bolt, Feral, Maverick and Pyro.

The following group of mutants was fighting alongside the Acolytes, trying to secure the High Evolutionary's Isotope E, which may be a cure for the Virus. Based on their words during the battle, it is assumed that they were all infected as well: Avalanche (although he may just have been trying to help Pyro), Fenris, Feral (confirmed), Omega Red (who may simply have been on a mission for his infected countrymen, or for a third party), and Random. Sinister himself may also have been infected (see X-Men #27).

The Legacy Virus Casualty List - With detailed info on the virus' strains and mutations.