Triple Formula 1 champion Niki Lauda has been re-admitted into intensive care in Vienna after suffering from a flu virus.

The Austrian, who currently sits as Mercedes non-executive chairman, had been recovering well from a lung transplant last summer and was hoping to start walking unaided as he bids to return to the F1 paddock in Australia.

However, this is a setback to those plans with doctors at the AKH hospital confirming Lauda's diagnosis to Austria's OE24 news outlet.

“There was an influenza case in his family, and he is treated to an intensive care unit with us,” spokeswoman Karin Fehringer said.

The decision to admit Lauda is precautionary with his immune system still weak from the operation in 2018 and it is hoped he will be discharged next week.