There are calls to tighten New Zealand's borders even further with concerns a single pre-departure test won't be enough to keep the growing COVID-19 pandemic out of the country.

It comes as the Government on Thursday agreed to a border exemption for some international students who were caught overseas during the pandemic.

As New Zealand makes the most of our summer of freedom, those at the border are working hard to keep it that way.

The pandemic spread is out of control in many countries and the Government is implementing some more restrictions to ensure it doesn't breach our borders.

New test requirements for people coming into the country come into force from Friday night where they'll need a negative test three days before they fly, but Professor Michael Baker says that's not good enough. 

"The trouble with getting a single PCR test three days before you get on a flight is that won't pick up incubating infection, it also won't pick up infections that you get after you've done that single test," he said.

Prof Baker would like to see travellers have two rapid tests and spend five days in isolation before coming to New Zealand but the COVID-19 Response Minister Chris Hipkins says that's too hard.

"It means we would have to have people around the world overseeing pre-departure quarantine in hundreds of different countries and that's simply not feasible," he says.

Prof Baker says the border is the risk and efforts should be concentrated there.  

"I think we should be focusing much more on the 300 people getting on flights overseas and coming back to New Zealand every day rather than the five million people here because we don't currently have transmission of the virus in the country.

"The real weakness for the next few months until we have high vaccine coverage is the risk from this quite small number of people coming back every day from countries where the pandemic is out of control and where we have these more infectious variants.

"These variants are much more transmissible at each point along the way, people can infect more people during the flight, more people in MIQ facilities in New Zealand and if these variants get established in New Zealand it would be a disaster for this country."  

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It comes as the Government agreed to allow 1000 international students to return to New Zealand from April.

"Allowing international students to come back into New Zealand doesn't increase the risk of COVID-19 coming in at all," Hipkins says.

But while other countries are rolling out their vaccines, New Zealand's are still months away.

"New Zealand will get its first shipments of vaccine towards the end of the first quarter, so in March, and we're looking to get those out the door and into people as quickly as possible when they arrive."

Border workers will receive it first, then other Kiwis from around June onwards.

The current priority for manufacturers is supplying vaccines to countries where thousands of people are dying every day from coronavirus.

Dr Nikki Turner says New Zealand is not top of that list.

"Even if we did [have the] virus circulating in New Zealand it would not be anything like what's going on in other countries with the death and devastation so for us to expect that we could suddenly jump the queue even further I suspect is very unlikely and not reasonable," she said.

So Kiwis will have to wait a few more months, but there are now concerns 

over which vaccines we will actually end up with.

Questions have been raised about the efficacy of the Oxford AstraZeneca jab, but Prof Peter McIntyre from Otago University says it would still save lives.

"What we're really interested in it preventing severe illness and there were only 10 severe cases in both the AstraZeneca and the Pfizer trials, and in terms of preventing severe disease bother vaccines were exactly the same."

As for fast-tracking the rollout, Dr Turner says there's no emergency in New Zealand, so there's no need.

"If we don't have to rush them then it would be inappropriate to rush them."

Professor Graham Le Gros says it's better to wait for the full data if we can.

"I would just calm it down a bit… take our time because we're in a good position at the moment we should just wait to see what happens, we're learning a lot at the moment, what's the best way to roll out this vaccine."

Professor  Le Gros is the director of the Malaghan Institute of Medical Research where they're creating our own New Zealand vaccine.

"We're making the next generation vaccines, we're very concerned that we need to prepare for the next pandemic, the other kinds of coronaviruses that are out there... 

"There's more than just COVID-19 out there, what are we going to do about it here in New Zealand, we don't want this to ever happen again."

Scientists working on our long-term protection while in the short term we're all keeping a close eye on our borders.