"Unfortunately, at the moment there is no news," triple world champion and Mercedes F1 chairman Lauda told the Austrian broadcaster ORF.
"But the rumours are constantly appearing, and it saddens me because every day I wait for some encouraging news that the situation is beginning to improve," he said.
"Recently it was reported that Michael can breathe on his own, which would be great news but then it turned out to be wrong," said Lauda, who is still scarred from his near-fatal Nurburgring crash in 1976.
"I am annoyed by these reports," he admitted. "Nevertheless, we are all waiting for better news."