Kiwis are likely to remain in the dark for months about when they will be able to travel around the world without needing to go into quarantine.
That's because experts say crucial data which could inform New Zealand's next move on international travel is still months away.
They are echoing Prime Minister Jacinda Ardern who this morning said there was insufficient data to support the idea of a vaccine passport, whereby people could enter New Zealand if they were vaccinated
"Until we are sure that vaccines are successful and effective in stopping you being able to pass on Covid to others, it won't necessarily stop outbreaks," Ardern told Newstalk ZB's Mike Hosking
"As soon as that data comes through and gives us that reassurance, we can change our plans up."
Hosking was critical of this approach, citing Singapore's decision to accept visitors into the country from next month who had a mobile travel pass with digital certificates of their Covid-19 tests and vaccines.
Otago University epidemiologist Michael Baker agreed with Ardern, saying the required data might not be available for a few months.
"[Singapore] has obviously felt that the evidence is strong enough," he said.
"There is evidence and I think the evidence is pretty compelling, but it's not as robust as we'd like."
Baker acknowledged that much of the current evidence indicated vaccines reduced virus transmission, as expected. However, there were several reasons why a vaccine might not sufficiently mitigate transmission but still avoid serious illness or death for the person vaccinated.
Once that data was available, Baker believed there were several countries New Zealand could include in its travel bubble, including Taiwan, China, Laos, Cambodia and Mongolia.
Fellow Otago University epidemiologist Nick Wilson repeated his colleague's prediction that robust data would not arrive until a few months' time.
He reiterated there was strong confidence vaccines reduced transmissions drawn from multiple avenues. These included several animal studies which indicated the vaccine could prevent infection and even when infection occurred, would limit the 'viral load' in the animal, reducing transmission likelihood.
Confidence was also drawn from evidence from Israel, where high vaccination rates have aligned with lower transmission rates. Wilson also referenced the general acceptance that virtually all vaccines reduced transmission.
"The only thing left is more evidence from the real world where vaccines are being rolled out," he said.
Wilson believed further countries, similar to those Baker referenced, could be added to New Zealand's current transtasman bubble with Australia in the coming months.
He explained this could be done in several different ways. The first would be to continue New Zealand's current focus on virus elimination and eventually eradication, by including countries with a similar focus, 'green-zone' countries, into a travel bubble.
Global virus eradication, which Wilson favoured, would require a commitment from the World Health Organisation (WHO) to promote a worldwide eradication strategy and for political leaders to support it, Wilson said.
Wilson was sceptical whether there would be complete political agreement in this matter and believed the WHO required further data to make such a commitment.
Another option would be a vaccine passport which would theoretically allow people from any country with proof of the necessary vaccination into New Zealand.
Wilson identified several issues with the vaccine passport option, namely the potential inequity of the process which would see people who needed to pay for the vaccine or couldn't otherwise access it, disadvantaged.
The final option was a combination of the previous two by which New Zealand would continue an open travel bubble with certain countries, but also allow vaccinated people from 'red-zone' countries into the bubble.
Once again, Wilson saw multiple issues with this proposal given the extensive coordination required with other countries in the bubble to approve how the process would work.
However, Wilson was optimistic global cooperation to eradicate Covid-19 could occur following similar efforts made in fighting Polio and Smallpox.