New studies released today, suggest that Homo Sapiens have a stronger immune system and more resistance to viruses due interbreeding with Neanderthals.
"Neanderthals and other extinct humans might have endowed some of us with the robust immune systems we enjoy today, scientists now find.
These genetic gifts might have helped our species as we expanded out of Africa, investigators added."
http://www.livescience.com/15754-neanderthals-immunity-boost-humans.html