Is a stable positive rate of <0.1% an indication of a fresh outbreak of SARS-CoV-2 infection?

Abstract

This letter gives a short analysis of the rate of positive SARS-CoV-2 tests in New Zealand and the restrictions that were implemented in response to these rates changing. Concerned about the growth of the number of positive cases of SARS-CoV-2 infection, the New Zealand government introduced stricter lockdown measures on August 16, 2020, and on August 18, 2020, it postponed elections planned for September. Growth in the number of positive cases was an artifact of the number of tests growing at a higher rate than the number of positive cases. The positive rate on August 16 was 0.05% (13 positive cases from 26,014 tests). On August 2, the positive rate was higher at 0.18% (three positive cases from 1,692 tests), despite the government considering that the virus was eradicated at this time. A better approach to this pandemic would be the development of policies based on the positive rate, not solely on positive case numbers, and to include viral load using reverse transcription polymerase chain reaction (RT-PCR) tests with an appropriate cycle threshold to properly identify infectious cases. It is also advised to protect vulnerable populations and avoid unnecessary limitations to the healthy population. The SARS-CoV-2 pandemic will last longer than several months, and the sooner life gets back to nearly normal, the better.