Jason Strain

A virus created when an artificial virus was exposed to undead killer Jason Voorhees, it was originally meant to be a cure-all and age retarding super drug. Those infected by the virus gain some select powers of Jason Voorhees, including superhuman strength and the inability to feel pain, but intelligence is severely reduced. Those infected with the virus can only be killed via decapitation. A cure for the virus is developed and released into the air and the original carrier, Jason (who was not affected by the airborne cure due to unique physiology) is rid of it when a heavy dosage of the cure is injected directly into his brain. This virus is in the book Friday the 13th: The Jason Strain by Christa Faust