Abstract
Increasing the test-per-case ratio was recommended to reduce the number of cases and deaths per capita. In particular, due to a synchronous increase in the number of tests alongside the rise in new cases and very high levels of the tests-per-case ratio, the COVID-19 pandemic in New Zealand was largely controlled before October 2021. After February 2022, an abrupt decline in the tests-to-case ratio led to a record number of cases and deaths at a relatively high vaccination level. Recent COVID-19 mortality rates in New Zealand are comparable with the global endemic level and the global flu mortality. Thus, the existing vaccines cannot reduce the number of COVID-19-related deaths per capita. Nevertheless, the lower values of case fatality risk CFR in more vaccinated countries in 2020–2022 still have to encourage people to be vaccinated, especially the elderly and persons with weak immunity. A recent huge increase in the case fatality risk is connected with the decrease in COVID-19 testing. Since many cases are hidden (asymptomatic), the estimation of real epidemic dynamics and correct CFR values needs complicated models, taking into account asymptomatic patients, re-infections, newborns, etc. To monitor the real epidemic dynamics (e.g., to calculate the rate of increase in the real number of infectious persons over time), a new reproduction number (recently proposed by the author) can be recommended.
Keywords
Efficiency of vaccinations, Testing efficacy, Mathematical modeling of infectious diseases, Statistical methods, COVID-19 pandemic, COVID-19 in New Zealand