A planned quarantine-free travel corridor between Australia and Singapore may take months to open because of delays to Australia’s Covid-19 vaccination program.

The two countries are “putting systems in place that will enable such a bubble to emerge between Singapore and Australia as it does now occur between Australia and New Zealand,” Australia Prime Minister Scott Morrison said at a joint virtual press conference after meeting Singapore Prime Minister Lee Hsien Loong on Thursday. He cautioned that any corridor is still some time away.

Such a bubble hinges on vaccination rates, Lee told reporters. “Once the majority of the population is vaccinated, it becomes much easier for us to contemplate these openings up,” he said.

That means an operational air-travel corridor could be months away, at least. Only about 5.5 million out of 26 million Australians have had at least one jab, meaning some border restrictions are likely to remain well into next year. Morrison’s government has abandoned its original October target to inoculate the population.

Singapore and Australia are among a handful of Asia-Pacific countries that have managed to contain the coronavirus and have been reluctant to ease border restrictions. Australia has largely closed its shores to non-citizens and residents since last year, while Singapore doesn’t allow most short-term visitors to enter, except for those under programs such as a green lane for business travelers.