National | Covid-19 Testing

NZ's 'fifth wave' of Covid-19 spurred on by new infectious subvariant

COVID-19 infections appear to have spiked over the end-of-year holidays

COVID-19 infections appear to have spiked over the end-of-year holidays as the country rides a fifth wave of infections and the introduction of a new variant.

Wastewater testing and hospitalisations are showing COVID-19 infections reached their highest levels since January 2023, said epidemiologist professor Michael Baker.

The new Omicron subvariant JN.1 is the fastest-growing variant, with it already accounting for over 60% of new infections in the United States and what is being called by some a “wave-on-wave” of new infections across the Tasman.

Genomic surveillance showed JN.1 caused 14% of sequenced cases reported in the week to December 15 and is currently the fastest-growing lineages among those ESR (the Institute of Environmental Science and Research) tracks.

“We’re very much in the middle of a fifth wave,” Baker said.

Professor Michael Baker said a new subvariant was likely to become dominant in NZ in the new year.

He said those tracking new infections relied on wastewater testing and hospitalisation numbers now that the self-isolation requirements had stopped and people weren’t reporting infections as readily.

“What it’s showing is that hospitalisations were at their highest level just before Christmas than they were for all of last year, so you’re getting up to 60 admissions a day of people who are sick enough to go to hospital,” he said.

Baker said the high infection rate in the fifth wave was a surprise, as he thought the waves would get smaller over time.

It should be noted, however, that the wastewater spike is still far below the waves seen in 2022. As are hospitalisation numbers.

Ministry of Health data shows that at midnight last Sunday, there were 355 people in hospital with COVID-19 and six cases in Intensive Care Units (ICU).

Between January 1 and January 7, there were 6558 new cases reported, with no additional deaths.

Otago University associate professor of immunology Dianne Sika-Paotonu agreed, attributing the growing infections to JN.1, which she said seemed to be becoming the dominant strain, though its impact on disease severity was yet to be determined.

Last month, the CDC in the US issued a memo saying: “There is no indication of increased severity from JN.1 at this time.”

She said that the growing number of those hospitalised could be down to the number of people being infected, rather than the severity of the infections caused by the subvariant.

The latest wave of infections is as high as it has been in the last 12 months (file photo).

Sika-Paotonu said Kiwis had become lax in mitigating the spread and said there were “really simple and effective steps” to manage the COVID-19 spread, such as vaccines and boosters, RAT tests, masks, and antivirals.