I’m pretty sure this is unique in the world, at least among such relatively large populations (about 20m in Aus and 5m in Aotearoa/NZ).
BBC reports this Monday (19 April):
The long-awaited Australia-New Zealand travel bubble means visitors no longer need to quarantine on arrival.
Thousands of passengers were booked to fly between the two nations on Monday.
Both countries have contained Covid outbreaks and kept infection rates low, largely due to tight restrictions.
Many Kiwis have “rellies” (relatives) in “Oz” (Aus), and vice versa. Quite a few people are taking advantage of the opportunity, while thousands of others are waiting to see how it goes.
Currently, travelers into Aotearoa must isolate for 2 weeks (that’s a “fortnight”) in government-run and -funded facilities. They are only allowed to enter in the first place if they have NZ residency or citizenship; a recent exception has been made to temporarily exclude travelers from India due to the heavy surge in covid in that country.
Those traveling between the 2 countries as of this week not only can avoid the quarantine, they are funneled through special sections of the airport that are off-limits to travelers from other areas where covid is still a big problem.
Plans for a vaccine passport, which would presumably enable vaccinated travelers from other countries to enter, are still in formative stages. As an American residing in Aotearoa with dual citizenship, I personally hope you all will be able to come visit this lovely place in the relatively near future. Those who refuse to get vaccinated will not be allowed in, however. I doubt many of them would care; their precious assault weapons are also illegal here.
UPDATE:
Since this was written 2 days ago (Kos would not let me publish it for unknown reasons), a 3-day lockdown has been declared in Western Australia, centered around Perth. WA has been temporarily excluded from the travel bubble, but the rest of Aus/NZ is unaffected.