Australian Border Force commissioner Michael Outram said a vacuum seal around the nation would prevent essential items like stem cells from entering the country.

"We don't want to stop all flights to Australia. We don't want to seal ourselves off," he told reporters in Canberra on Wednesday.

"Similarly with the ports, there's a lot of containers coming to Australia with goods that we need as a country."

But he insisted the ABF was ready for anything if the government decided to take more drastic action to contain the disease.

Passenger movements through Australian airports were down by around 5000 on Monday, while 23 flights were cancelled on Tuesday.

The 14 cruise ships which had left are returning to ports, with no reported sickness onboard any of them.

About 12 border force workers have been tested for coronavirus with no positive results so far.

Mr Outram said his staff not contracting the virus should reassure other frontline workers wearing personal protective equipment.

"If you follow procedures, you wear your PPE, it's a very, very low risk," he said.

Border force officers are preparing to welcome home Australians from overseas after the government advised people to return.

At airports, people will receive quarantine information at check-in and on the flight before signing a written declaration to self-isolate for 14 days after arriving.

Mr Outram said there had been little disagreement from people returning.

The commissioner has also told his officers to keep the pressure on drugs and other border crime.

"Whilst this is going on and all the focus of the media and the world is on COVID-19, we're not going to drop the ball," he said.

Australian Associated Press