Ministry of Health data shows there were more than 1 million scans between Sunday and Monday, an increase from approximately 818,000 between Saturday and Sunday.
"We've got MIQ all over the country [and] people are still travelling ... the virus can metaphorically teleport across the country in a short period of time.
"People might say 'I live in the middle of nowhere, no one is going to get sick' but these places are not immune from the virus."
News of a low number of people scanning in at location destinations was nothing new, Chen says: "[We saw it] all through the latter half of last year as well. The long-term behaviour change hasn't been ingrained within some people."
He thought as people lost their connection as to why they are using the app, they automatically think nothing will happen if they never scan in.
The three community cases - a mother, father, and daughter from Papatoetoe, South Auckland - have the dangerous United Kingdom variant of Covid-19.
And although they had not been using the tracer app often, 21 locations and times of interest had been identified between Auckland and New Plymouth.
The Ministry of Health also confirmed contact tracing identified 10 close contacts outside of their household, six returned negative tests and four are pending.
The number of people using the tracer app is small. There is a dedicated group of around 400,000 to 500,000 people who are scanning religiously, Chen says.
While the number of scans increases around community cases, the numbers will inevitably fall if and when the nation goes back to normal, he said.
This is not good enough for Chen, who urges app users to put the pressure on family, friends, workmates and neighbours to get on board.
"Actually have conversations with people saying, 'I feel there is risk and if you can participate in this system with me, that can help reduce the level of risk for all of us'," he said.
Local resident Vaughan Tilley was one of those who used his phone to sign in at the Rotorua Central Mall and told the Rotorua Daily Post it was "important for everyone to do their bit".
He said with the new powerful virus strains, everyone needed to "keep this at bay", especially for the city's vulnerable.
"Some people couldn't care less."
Tilley said given his age, he needed to "take care".
Raywyn Bidois went out of her way to track down the code as she said she "just wanted to stay safe".
"It's all of our responsibility to look after the community right now."
She admitted she had been a "little slack" in recent times but had jumped straight back in, either signing in when she entered or left a place, she said.
A man, who asked to remain anonymous, said he normally resided in Europe and had seen how "awful" and "devastating" Covid-19 had been there.
He said it was crucial New Zealand protected the health it had while it had it.
"I'm just doing my bit."
Rotorua Central Mall general manager Peter Faulkner said community tracing and QR codes were "critical" when it came to keeping on top of Covid-19.
He said the mall had erected signs at all three entrances reminding people to sign in and each retailer in the mall and the entrances had its own QR codes.
Most people who came and went from the mall "did one or the other", he said.
He said he had noticed an increase in people signing in on Monday compared with the past few weeks.
