Te Whatu Ora is going to court over a couple who do not want their sick baby to have surgery unless doctors use blood from unvaccinated donors.

Anti-vax campaigner Liz Gunn has posted a video interview with the couple online, apparently from their room at Starship Hospital.

They say the baby urgently needs open heart surgery and they want the blood to come from people who have not had the Covid-19 vaccine.

The NZ Herald is reporting Te Whatu Ora is applying for guardianship of the child.

The health authority told RNZ the decision to make a court application is always made with the best interests of the child in mind and following extensive conversations with the whānau.

It says it knows it can be worrying for parents who have a sick child and who are making decisions about their care.

It would not comment further as the matter is before the courts.

The Blood Service says it did not keep blood for vaccinated and unvaccinated donors separate and there is no risk from the Covid-19 vaccine.

"It's definitely one of those really distressing cases for everyone involved because both the healthcare team and the parents are trying to act in the best interests of the child but they have this really significant disagreement about what that looks like in this case," says University of Otago bioethics lecturer and research scholar Josephine Johnstone.

It's a very rare case that gets this far, she says

"Parents have a lot of decision-making authority over their child's life - there's a huge zone of discretion for parents to make decisions including about medical issues - but there are limits to that, and this is one of those tragic cases where the limit has life and death consequences."

-RNZ.