The Nobel committee said the trio's research has paved the way for "promising new strategies" that will fight all sorts of conditions and diseases. Semenza worked in the 1990s on identifying a protein complex that binds to cells' DNA in response to levels of oxygen in the cell's environment.
Awarded American scientists William Kaelin, and Gregg Semenza, as well as British scientist Sir Peter Ratcliffe's findings have affected our day to day life from exercise, to how we cope at high altitudes, and to fetus development in the womb.
The nominees in all categories - whose names are never announced and can not be revealed until 50 years have passed - are picked by members of academies, university professors, scientists, previous Nobel Laureates, and members of parliamentary assemblies.
Thunberg's category, the victor of which will be announced on Friday, is one of five created by Alfred Nobel in his third and last will in 1895, which left much of his wealth to establishing a prize for those who "conferred the greatest benefit to humankind" during the preceding year.
Laureates in the fields of physics, chemistry, literature and peace are also due to be announced in the coming week, followed by economics next week.
At the same time, William Kaelin and his group from the Dana-Farber Cancer Institute, in collaboration with others, discovered that cells lacking the von Hippel-Lindau gene (connected to cancer) were more likely to show signs of hypoxia.
Andrew Murray of the University of Cambridge said the three laureates' discovery was fundamental to understanding how to combat diseases of the heart and lungs as well as numerous cancers.
They identified HIF-1a, which appears when oxygen levels are low and disappears when oxygen levels are normal.
"So I think that's the way real science works, it doesn't work by putting blinders on people and trying to make believe they're working on an engineering problem when they're really working on a scientific problem". "If, even then, the prize can not be awarded, the amount shall be added to the Foundation's restricted funds".
The 2019 Nobel Prize in literature will be announced on Thursday, Oct. 10.
But don't worry, we will have a victor this year.
Alfred Nobel, the Swedish scientist and inventor who made a vast fortune from his invention of dynamite in 1866, ordered the creation of the famous Nobel prizes in his will.
The economics prize will be awarded on October 14.
Wangari Maathai became the first black woman and first environmentalist to win the Nobel Peace Prize in 2004.