There are growing calls from elderly advocates for kids to give trick-or-treating a miss this year, over fears they could spread coronavirus.
While there's no evidence of any current community transmission of the deadly virus in New Zealand, it can spread asymptomatically - and kids who contract it often show no symptoms, and could be unaware.
"Although you might feel absolutely fine and feel perfectly well, the person who opens that door isn't necessarily going to know that," Age Concern Auckland CEO Kevin Lamb told Newshub.
"They might be frightened, they might be scared."
Halloween falls on a Saturday night this year, potentially increasing the number of children who want to go door-to-door collecting candy.
The Ministry of Health says anyone offering up lollies should put up a QR code so trick-or-treaters can check in, which would help with contact-tracing should there be a case. At the very least, parents should make a manual note of where their kids have been.
Lamb says kids should only visit homes of people they know, to assist not just with tracing but also the safety of elderly and immunocompromised.
"They might be in that vulnerable bracket of older people or people with immune deficiencies, and they don't want to be face-to-face with strangers on their doorstep... Some people are going to be a little bit scared and a little bit alarmed."
And people offering treats should consider putting them in a bowl outside, avoiding contact altogether.
Police say parents should be out with their kids this year - not just to scan QR codes, but keep an eye on them.
"The law talks about 14 being a general age [up until when] people need to be supervised, but it's much more than that - it's about the maturity of your child, the ages of the other people in the group they're going out with," said Supt Eric Tibbott.
Tibbott says parents should also check gifted candy before it's eaten.
University of Otago infectious disease expert Michael Baker told NZME earlier this month at level 1, trick-or-treating should be okay, and his colleague Nick Wilson said it was "small bixies" compared to the risk of adults out nightclubbing.
Earlier this week Grey Power also begged kids to stay at home, citing much the same reasons as Age Concern.
"It would be almost impossible to have contact tracing," Auckland Grey Power president Gillian Dance told Newshub. "They have no knowledge of who you are, and you have no knowledge of them. I think it's a bit risky."
What to expect on Saturday night
New figures from Trade Me have found more people are getting in the Halloween spirit.
There have been 50,000 searchers for costumes on the site in the past two weeks.
A few Harley Quinn and Harry Potter lookalikes should be expected - taking out the first and second places in this year's list of most popular costumes.
A Trade Me spokesperson said many people have been feeling groovy, with '80s costumes coming in at number three.
Rounding out the top 10 are traditional Halloween outfits such as witches, vampires, skeletons, pirates and clowns, with dinosaurs and the Joker also popular.