New Zealanders are scanning QR codes with the COVID Tracer app at almost half the rate they were two months ago.

It's prompted another reminder from the Ministry of Health on Wednesday, urging people not to become complacent.

In November, there were an average of 866,000 scans per day.

That dropped to 516,000 in December and has slipped to 465,000 per day in January so far - almost half of November levels.

Director General of Health Dr Ashley Bloomfield said people needed to stay on high alert as the virus spread quickly, and cases continued to increase globally.

He asked people to take the time to scan in with the app, or record their own diary so contact tracing could take place quickly if there was another outbreak.

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"We can't afford to get complacent - especially given the increasing numbers of new cases we're seeing in many other countries. We've seen how quickly the virus can spread. We all have a responsibility to support contact tracing by keeping a record of our movements, either with the app or by another method such as a diary," Bloomfield said.

"It's incredibly important we all scan the QR codes wherever we see them, as the more we all scan, the safer we'll all be.

"Make summer unstoppable - scan, scan, scan."

The NZ COVID Tracer app now has 2,439,100 registered users.

Poster scans have reached 151,801,799 and users have now created more than 6,127,918 manual diary entries.