As the deadline for NSW residents to return to their home state or face 14 days of forced quarantine passes, Sydney Airport looks more like a medical centre as passengers fly in from Melbourne.

As of 12.01am on Wednesday, officers blocked major roads between NSW and Victoria in a desperate attempt to slow the growing COVID-19 spread sweeping the Garden State.

NSW residents were told on Monday to return home from Victoria or face 14 days of forced quarantine. Victorians are now banned from entering NSW unless they receive a permit or are considered to be an essential worker. Defying the new public health order carries a maximum penalty of $11,000 and six months in jail.

Sydney Airport was filled with police and health officials, with some arriving passengers being tested for the virus.

During the lead-up to the border closure, airlines made the decision to slash services between Sydney and Melbourne, along with other destinations between NSW and Victoria, in response to the state line shutdown.

On Tuesday, Qantas reduced its six scheduled flights between Melbourne and Sydney to five, and Virgin Australia cut its two flights to one.

In a statement sent to news.com.au, a spokesperson for Qantas said flights will be "significantly reduced" until borders reopen.

"Qantas and Jetstar are significantly reducing flights to and from Melbourne following the decision to close the NSW border," the statement read.

"We'll continue to operate limited flights for essential travel only."

For Australians wanting to apply for a permit to travel between Victoria and NSW, there are about a dozen exemptions, including NSW residents returning home, carers, seasonal workers, students or people applying on compassionate grounds.

Originally published as Grim reality of flying into Aussie airport