The world-wide lockdowns in 2020 due to the Covid-19 pandemic brought several things: clear skies, cleaner air, and for New Zealand, no more influenza.

In New Zealand, the influenza virus circulation was almost non-existent during the 2020 winter, a 99.9% reduction compared with previous years, likely because NZ’s use of stringent lockdowns had markedly changed human behaviour.

The study published in Nature journal, called “Impact of the COVID-19 nonpharmaceutical interventions on influenza and other respiratory viral infections in New Zealand” helps us understand, and be informed before future pandemic influenza preparedness.

The results of the study find that Influenza activity in New Zealand during the winter of 2020 was very low as confirmed by multiple national surveillance systems. From May to September 2020, hospital-based severe acute respiratory illness (SARI) surveillance (catchment population of 1 million people) showed very low SARI incidence rates, all below the seasonal threshold defined by the reference period of 2015–2019.

The national International Classification of Diseases-coded (ICD-10AM-VI code J9-J11) influenza hospitalisations for all NZ public hospitals showed a significant decline. From 1 January to 31 July 2020, a total of 291 influenza hospitalisations were coded: pre-lockdown 238 (81.8%), lockdown 33 (11.3%), and post-lockdown 15 (5.2%).

New Zealand, a southern hemisphere country with a temperate climate, has a well-established influenza circulation pattern with peak incidences in the winter months. Multiple surveillance systems showed that there was no annual laboratory-confirmed influenza outbreak or epidemic detected during the 2020 winter season. Remarkably, influenza virus circulation was almost non-existent during the 2020 winter, a 99.9% reduction compared with previous years.

While the study is collected through data from hospitals, one nuance remains how many people were swabbed only for Covid-19 that would normally have been swabbed for flu?

New Zealand on Monday reported two new coronavirus infections which sent New Zealand’s biggest city into lockdown and are due to the UK variant of the disease, the first to be detected in the country. It was the first clampdown in nearly six months in the Pacific island nation, which has been widely praised for its handling of the pandemic, with just 25 deaths in a population of five million.

Auckland spent more than two weeks in lockdown last August after a virus outbreak was linked to a worker handling imported frozen freight, but New Zealand has largely been enjoying relaxed restrictions for months.

Several cases of Covid-19 were also detected in the city three weeks ago, before being traced back to a hotel where the people had completed quarantine after arriving from overseas.

Ardern has been widely praised for her management of the pandemic, with New Zealand recording fewer than 2,000 infections.

The country closed its borders and implemented a strict five-week lockdown in March and April last year, with occasional virus outbreaks since then being quickly contained.