Northland District Health Board said it changed the age limit when it realised people over 65 had been offered their flu vaccine last week.
Those who took it would have to wait two weeks before getting their Covid-19 immunisation, meaning fewer people were eligible for their Covid-19 shot.
Northland DHB said the age was changed to reduce any vaccine waste and to accommodate the age of Northland's rural communities.
There was a large queue of people waiting to get the Covid-19 vaccine when the Whangārei clinic opened at midday today, but not everyone was aware of the age change.
Chantelle Thompson brought her grandparents from Whangaruru to get the vaccination - but she said she would have brought more whānau had she known.
"I knew for kaumātua and kuia, just as long as they were over 65, I didn't realise it had dropped down to 50 - I had an uncle who was actually interested and in the same area, same house, and he is 50.
"So I could have brought him along if I'd known."
Robin Grieve turned up because of the age change - but he questioned why younger Northlanders had jumped ahead of higher priority groups.
"It just seemed to me it wasn't part of the programme so I was very surprised."
He said information around the vaccine seemed haphazard.
"I'm conscious of the fact that my mother, who is 95 and has heart failure, hasn't had her vaccination yet, and her group is vaccinating, but our group - who is over 50 - is not even on the list until Group Four.
"But I'm happy to get vaccinated either way."
While the line moved quickly, there were waits of up to two hours at times for the vaccine.
Gloria Reid waited through the patchy rain to get her vaccine, and said she was surprised the age limit had changed so quickly.
"That was a disappointment, because I was in the over 75 age group and I thought we would get in nice and quickly."
Te Hau Ora O Ngāpuhi chief executive Te Ropu Poa said while dropping the age limit was great, communication around the vaccine in general could be better.
"Especially those who live in rural areas so they are able to come into town and they know exactly where to go - there requires a few questions here and there that we've noticed, people have been asking where the sites are and when is it their turn and how can they get a vaccination.
"That shows us that we need to work harder on the communication."
Te Hau Ora O Ngāpuhi will be administering vaccines from a clinic it is running from Friday in Kaikohe.
Northland DHB said it had administered 6252 Covid vaccines as of this morning.
