Hundreds of passengers thronged Australian airports on Monday as an open border system began with New Zealand, a pandemic milestone that allows Australian residents to fly there for the first time in over a year without having to quarantine for two weeks.

Though most Australian states have allowed quarantine-free visits from New Zealand residents since late last year, New Zealand had enforced isolation for arrivals from its neighbor, citing concern about sporadic virus outbreaks there.

The travel bubble means Australians and New Zealanders are now free to go between both countries without needing to apply for an exemption or spend some time in quarantine.

Wilana Rawiri, 29, told Australian Broadcasting Corporation (ABC) that hotel quarantine was a "deal-breaker."

The 29-year-old told ABC that the travel bubble came in time as she blessed that the plan would open up in time for her to attend a funeral.

The first flight headed for Auckland from Sydney was reported to take off about 7:00 am. "I had to be on the first flight out," Heather Lyberopoulos, 56, who is anxious to reunite with her sister, said in the interview with ABC.

The 56-year-old told ABC that "it's some sort of normality for me to be able to go home. I am grateful."

"It is the first time in 400 days that people can travel quarantine-free and we are adding 16 return flights a day to New Zealand, and they are full," Qantas Chief Executive Alan Joyce told ABC on Monday.

The open border will help drive the economic recovery for both countries and reunite thousands with families and friends, Australia's Prime Minister Scott Morrison and New Zealand's Prime Minister Jacinda Ardern said in a joint statement.

Australia was New Zealand's largest source of international tourists before the pandemic, accounting for about 1.5 million arrivals or 40 percent of total visitors in 2019.

"It is truly exciting to start quarantine-free travel with Australia. Be it returning family, friends or holiday-makers, New Zealand says welcome and enjoy yourself," Ardern said.

Both Australia and New Zealand had largely closed their borders to non-citizens and permanent residents more than a year ago, helping to keep their COVID-19 numbers relatively low compared with several other developed countries.

Australia has recorded just over 29,500 virus cases and 910 deaths since the pandemic began, while New Zealand has had just over 2,200 confirmed cases and 26 deaths.

Morrison and Ardern warned travelers to prepare for disruptions to travel arrangements at short notice in the event of COVID-19 outbreaks, and said the risks of quarantine-free travel will be under "constant review."

Both leaders also flagged the possibility of extending quarantine-free travel to other countries in the Pacific region when "it is safe to do so."

There are some other travel bubbles in effect or on their way. Australian Deputy Prime Minister said in March that the country was working with Singapore for a potentially travel bubble beginning in July.

Singapore and China's Hong Kong Special Administrative Region were reported to delay a travel bubble, which was planned to open on November 22, due to a spike in coronavirus cases in Hong Kong. It's still uncertain when the two will resume the travel bubble. 

(with input from agencies)