New Zealanders travelling home from overseas are unable to book managed isolation as the system is full.

The government is yet to release dates beyond May, and it's stopped re-releasing people's cancelled bookings while it accounts for the loss of the Pullman Hotel.

People logging into the booking website will encounter a calendar showing dates from today through till May 31 - each struck out with a little grey cross.

Advice from Prime Minister Jacinda Ardern on Sunday, to "keep checking" for regular cancellations, was promptly superseded yesterday by the Ministry of Business, Innovation and Employment, which runs the hotels.

"Cancelled vouchers that would normally be released back into the Managed Isolation Allocation System will be kept as additional contingency for a short period as we navigate through this current situation," it says.

Without the Pullman Hotel, MBIE says it still has some contingency left in the system - but that comes as no help to people like Elmarie Els' daughter who wanted to fly home to New Zealand before she gives birth in May.

She is now preparing to hunker down in Dubai, but expects she will need a passport for the child before she can try booking managed isolation again.

Els wasn't sure when she would be able to meet her grandchild.

"It is very stressful. You can imagine being 22 weeks pregnant and having this stress and not knowing if you'll make it home or not and what's going to happen if they can't," she says.

"I know lots of people are saying 'close the borders' but as a mum you just feel stressed, all the time."

Motueka travel agent Jeremy Matthews has customers lining up for managed isolation bookings.

He says it took about half an hour for April and half of May to book out.

"It really was like watching sand drip through an hourglass. There's quite a deep level of frustration about how quick it is and I think it reflects a lot of demand and also a lot of panic."

He knew of people already making online logins in preparation to secure space in December - and said people who had hoped to snap up someone else's cancelled booking in the meantime were likely to feel despondent.

"At best it will be frustration and at worst it will make people who are in a very stressful situation - it will put them in a pretty awful space really."

Every spot in managed isolation and quarantine is booked out until the end of May, and no dates beyond then have been released Photo: SCREENSHOT.

Asked if the government will consider making more spaces available in managed isolation, Ardern gave the same answer on Sunday she has repeated for weeks.

"No we are not currently increasing capacity. Something that we have to keep in mind is that with every person that returns, there's an increased risk to New Zealand. We have to manage that risk by making sure we have numbers coming back that we can manage as safely as possible."

Els believed there could be an opportunity to free up space, with her son-in-law having received the COVID-19 vaccine in Dubai.

Her daughter is also due to receive it soon and she said they wouldn't need to take up space in a border hotel.

"We're thinking - could they then isolate with us, rather than going into managed isolation? More and more people are going to be in this situation now so they don't pose a threat," she said.

COVID-19 Response Minister Chris Hipkins says the Pullman Hotel will likely be empty by Saturday, and stay offline for about two more weeks.

In a statement, MBIE says the Managed Isolation and Quarantine system has a contingency of around 400 rooms for emergencies, including when a facility can't accept new arrivals "as is currently the case with the Pullman Hotel".

"There is still contingency in the system, even with the Pullman not accepting new arrivals. The system is designed with this in mind and it is safe and manageable. This current situation is an excellent example of why MIQ operates with a contingency set aside."

-RNZ/Katie Todd.