The racing driver's family also said in a statement that they are sure he will wake up from his coma.
"We are, and remain confident, Michael will pull through and will wake up," the statement on behalf the driver's loved ones read.
"There sometimes are small, encouraging signs, but we also know this is the time to be very patient.
"Michael has suffered severe injuries. It is very hard to comprehend for all of us that Michael, who had overcome a lot of precarious situations in the past, has been hurt so terribly in such a banal situation.
It was clear from the start this will be a long and hard fight for Michael, and we are taking this fight on together with the team of doctors, whom we fully trust.
"The length of the process is not the important part for us.
"It is heart-warming to see how much sympathy his family is shown and I can say the family is extremely grateful for it.
"However, it should not be forgotten Michael's family is dealing with an extremely intimate and fragile situation.
"And I would like to remind all of us Michael has always actively kept his family out of the public eye and consequently protected their private lives.
"We try to channel all the energies we have toward Michael and we firmly believe this will help him, and we believe he will also win this fight."
Michael, 45, has spent 11 weeks in an induced coma which doctors brought on following two operations to remove blood clots from his brain.