Covid Tracer QR code posters can be created here.
One commenter asked how young kids would scan QR codes if they didn't have a phone.
Another asked why they need to scan '? They're not even coming inside the house though'.
Deputy director of public health Dr Harriette Carr said New Zealand is lucky to be in Covid-19 alert level 1, meaning children can go trick or treating, but she said there should be precautions.
"If anyone is self-isolating or been told that they need to stay away from others then we recommend that they put a sign outside their house, not to trick or treat.
"Equally, anyone that is sick or feeling unwell should not go trick or treating, and should also put a sign outside their house. That's a really good way people can both protect themselves and protect others.
"Anyone handling food or lollies should always make sure their hands are clean, so wash hands, or if children are going trick or treating, they've got hand sanitiser with them if they're going to be eating food or handling food.
"Then there's also people noting down where they've been. So that might be a manual entry if there's a parent going with the children noting down which houses they're going to.
"For people who are participating from their houses, there is the opportunity for them to download the Covid QR code for their house so people can scan that.
-In addition with RNZ