Spring has begun, but winter illnesses remain at high levels with the country experiencing a late peak.

Research shows serious seasonal respiratory illnesses, including influenza and RSV, are circulating at a later time in the year than usual.

Influenza-like illness rates in the South Island have risen above the national average, reaching levels not seen since the Covid-19 Omicron community wave in 2022, Healthline data shows.

PHF Science public health physician Dr Sarah Jefferies said reports of influenza-like illness have been rising since the middle of the year.

“Our surveillance systems are showing that as of the end of August, New Zealand is experiencing a late peak in seasonal respiratory illness in the community, and indicators show this is currently particularly affecting the South Island.”

The FluTracking weekly report shows a later, higher peak for flu symptoms this year. Photo / FluTracking

The influenza season typically runs from May to October, but following Covid 19, respiratory illness peaked earlier, in June or July.

“This year, however, weekly reports of community influenza-like illness have risen steadily since May and are still climbing into late August.

“While this is later than recent years, weekly rates remain below the national peaks recorded between 2022 and 2024.”

Laboratory testing indicates that influenza and RSV are driving the spread of illness.

“This year’s burden is being driven by multiple viruses, particularly two strains – influenza A [H1N1] and B viruses – alongside a prolonged RSV season and ongoing Covid-19 spread.

“These influenza viruses can hit young people harder, but even healthy adults can become seriously unwell.

“The good news is that this year’s seasonal influenza vaccine is a good match to the strains circulating and will provide strong protection.”

Jaime Lyth is a multimedia journalist for the New Zealand Herald, focusing on crime and breaking news. Lyth began working under the NZ Herald masthead in 2021 as a reporter for the Northern Advocate in Whangārei.