Uncertainty remains the dominant mood as Formula 1 teams prepare for the opening races of 2020.

Amid the coronavirus crisis, which has already claimed the Chinese GP, the Melbourne season opener appears safe for now but strong doubts about Bahrain and Vietnam persist.

F1's Italian-based contingent is most affected, as staff for Ferrari, Alpha Tauri, Pirelli and to a lesser degree Haas and Alfa Romeo face the prospect of long quarantine periods.

"It would be a huge disadvantage," Alpha Tauri boss Franz Tost is quoted by RMC Sport.

F1 sporting boss Ross Brawn has said that if teams like Ferrari and Alpha Tauri cannot race, the grands prix will not go ahead without them.

"We also need to understand the Pirelli problem," said Ferrari team boss Mattia Binotto, referring to the fact that staff working for F1's official tyre supplier come from the deeply coronavirus-affected Italian north.

Ferrari and Pirelli have now called off Thursday's scheduled test of the 2021-spec 18-inch tyres at Fiorano.

"As a global sport, we are in an incredibly serious situation," said Claire Williams.

"We have a lot of responsibility to react appropriately to the latest events with lightening speed.

"Everyone in Formula 1 wants to do what they are passionate about, which is race, but the bottom line is that people must be kept safe."

Until now, F1 CEO Chase Carey has put a brave face on the crisis, but even he admits he isn't sure what is going to happen next.

"The situation is constantly changing," he said. "It is really difficult to look too far into the future. It's changing so quickly.

"We are continuing to prepare so that we can proceed with the races we have planned, but we have to take decisions that are right for everyone - the spectators and the competitors."