In its citation the Karolinska Institute writes of their work:
"These two discoveries have provided humankind with powerful new means to combat these debilitating diseases that affect hundreds of millions of people annually. The consequences in terms of improved human health and reduced suffering are immeasurable."
They will share this year's prize of SEK 8 million (USD 960,000).
Medicine is the first of the Nobel prizes awarded this year.
The prizes for achievements in science, literature and peace were first awarded in 1901 in accordance with the will of dynamite inventor and businessman Alfred Nobel.