Vaccinators whose names were published on a US website after a Te Whatu Ora data leak are feeling nervous and under threat, says a nurses' union.

Te Whatu Ora has been notifying at least 12,000 people - mostly vaccinators - who had their names released in last year's breach.

The Nurses Organisation kaiwhakahaere Kerri Nuku says several nurses had been in touch after getting a call.

"[They're] nervous that their information's out there in the world and somewhat feeling threatened. They were doing the best job possible and it's turned on them so they're feeling vulnerable and really let down," she says.

Te Whatu Ora says most of them had only their names published.

But Kerri says that was enough to make them worry.

The husband of one nurse had received an abusive message about his wife because she was a vaccinator, Kerri says.

It could be a coincidence, but it did show that those kind of threats were out there, she says.

"It highlights the anxiety and the situation that these nurses are feeling at the moment."

Kerri says many nurses who had received a call from Te Whatu Ora had in turn been calling fellow vaccinators to warn them they may be on the list.

Te Whatu Ora had apologised for the breach and says it was working on making its systems better so a similar incident could not happen again.

Chief executive Margie Apa says last week the victims of the leak had been doing their best to keep the country safe.

Support would be in place for any of the who needed it, she says.

Barry Young, a former Te Whatu Ora employee, has been charged over the leak.

- RNZ / Rowan Quinn