The government considered setting up another managed isolation hotel to cope with the rush of New Zealanders coming home before Christmas, but doesn't have enough staff.
Managed isolation facilities are already booked out for most of the time before Christmas - only a short chunk in mid-November remains.
That means a flight of Russian fishing crew who were due to arrive this month is now delayed indefinitely.
Head of managed isolation and quarantine, Air Commodore Darryn Webb says new hotels can't be quickly set up for isolation use.
People arriving in New Zealand from today must have a voucher confirming they have a place in a managed isolation facility before boarding their flight.
A new community case of Covid-19 was confirmed in Christchurch last night.
A staff member working at the managed isolation facility where the first group of international fishing crew members has tested positive with the virus.
Thirty-one of the 237 mariners staying at the Sudima at Christchurch Airport are infected with Covid-19.
