So-called "gamification" features are being added to the NZ Covid Tracer app in a bid to get more people scanning posters, more of the time.
After 14 consecutive days of scanning or diary entries, users will be awarded a spiral success badge.
The latest update also displays lives statistics on how many of the Team of 5 Million are using the app, and other stats.
While one Twitter wag suggested KFC vouchers would be more effective, Massey University psychology professor Dr Aaron Drummond says the new features are good positive reinforcement techniques that should help with the "cultural tightness" that a recent Cornell study found helps to reduce illness and death from Covid-19.
Auckland University researcher Dr Andrew Chen notes the Ministry of Health has also made some tweaks under the bonnet - which could be particularly useful for those with older phones.
"The MoH has been quietly been releasing other updates in recent weeks. The most significant one is that they upgraded the app to version 2 of the Apple/Google Exposure Notification Framework that powers Bluetooth Tracing, which means that it is now compatible with more iOS devices, particularly the iPhone 6 [firs released in 2014]," Chen says.
There have also been tweaks that should see NZ Covid Tracer run faster on older Android phones.
"So if you previously couldn't use Bluetooth Tracing, it is worth trying again to see if it is now compatible with your phone," Chen says.
The app can now also access your phone's torch, to make it easier to scan posters in the dark.
Some 2.77 million people have now downloaded NZ Covid Tracer app.
Of those, 1.27 million have enabled automated Bluetooth tracing.
Poster scanning remains low, outside of lockdown scares.
But yesterday (April 7) only 434,168 people scanned at least one poster (there were 828,029 scans overall), with participation dropping to as low as 262,137 on Easter Sunday (where, again, each user scanned around two posters).
Chen says modelling indicates "We want to see at least four million QR code scans a day, and at least two million people participating in Bluetooth Tracing under Alert Level 1 settings."