Jakobsen careered into the barriers whilst jostling for position with Dylan Groenewegen at the end of the first stage of the Tour of Poland on Wednesday.
The rider was treated at the scene and placed into a medically-induced coma after sustaining a substantial loss of blood, a cerebral cranial injury and a broken palate.
And a doctor who treated the Deceuninck–Quick-Step rider told reporters that his condition was serious enough to be considered life threatening.
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“Jakobsen has extremely serious injuries and his life is in danger,” said Dr. Barbara Jerschina, as reported by naszosie.pl.
"We did everything that could be done, but the situation was difficult. It was difficult to intubate as he has a very serious cerebral cranial injury and a broken palate but larynx was able to be supplied with oxygen all the time and his heart was working well."
Four other riders - two of which were hospitalised – and a race official were also injured in the horror crash at end of a hilly 195.8km course from Stadion Slaski to Spodek Katowice.
The UCI would strongly condemn Groenewegen for his role in the crash, calling his behaviour "unacceptable" and explaining that they "immediately referred the matter to the Disciplinary Commission to request the imposition of sanctions commensurate with the seriousness of the facts".
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'Skull fracture, bruised brain, 10 teeth gone' – Jakobsen on horror crash in Poland