French Formula One driver Jules Bianchi remains in a "critical but stable" condition in hospital in Japan, his family said on Thursday.
In a statement on the Marussia driver, who crashed into a recovery vehicle during the rain-lashed Japanese Grand Prix on October 5, they said there was "no new information to give".
The Bianchi family thanked fans for their continuing support, adding that they felt a need to keep everyone updated despite having no news.
The statement, issued on the eve of opening practice for the United States Grand Prix - from which Marussia and fellow-strugglers Caterham have withdrawn - read: "It will be four weeks this coming Sunday since Jules` accident and he remains in the Mie General Medical Centre in Yokkaichi.
"His condition continues to be classified by the medical professionals here as critical but stable.
"Although we have no new information to give, we recognise that there are a huge number of people all around the world who are supporting Jules and willing him on in his fight.
"We owe it to his many fans to acknowledge the continued outpouring of messages, and to provide some information, however brief it may be."
It concluded: "We will provide a further update when it is appropriate to do so. In the meantime, thank you to everyone who continues to keep Jules in their thoughts and prayers."