Seasonal Flu Signals From New Zealand, Australia & Japan

Credit CDC

#19,322

A week ago, in Japan MHLW Reports Unusually Early Start to the Fall Flu Season, we saw Japan's earliest start to their flu season since the 2009 H1N1 pandemic. The Ministry of Health's most recent (Sept 4th) update indicates that flu reports have jumped 60% since last week's figures were announced, with the highest rates reported in Okinawa Prefecture, followed by Iwate Prefecture, and Niigata Prefecture.

According to media reports today, the deployment of this year's seasonal flu vaccine (scheduled for late September) may begin for the elderly as early as this week. 

 
Meanwhile, in New Zealand, at a time when the Southern Hemisphere's flu season is usually winding down, the PHF Science website reports a late season surge in hospitalizations for (mostly) influenza. 

Most hospitalized (see chart below) are children aged 0-4 and the elderly (65+). 

Queensland, Australia is reporting a similar late-season surge (see chart below), although it has yet to reach the heights of last year's flu epidemic.

 

While none of this is necessarily predictive of the broader Northern Hemisphere flu season ahead, it is worth noting that after the late arrival last year of a `drifted' subclade K H3N2 virus, and recent antigenic changes observed in both H1N1 and Influenza B, the WHO has recommended changes to all 3 components of the 2026-2027 flu vaccine.

Overview

For vaccines for use in the 2026-2027 northern hemisphere influenza season, WHO recommends the following:

Egg-based vaccines

• an A/Missouri/11/2025 (H1N1)pdm09-like virus;

• an A/Darwin/1454/2025 (H3N2)-like virus; and

• a B/Tokyo/EIS13-175/2025 (B/Victoria lineage)-like virus.


Cell culture-, recombinant protein- or nucleic acid-based vaccines

• an A/Missouri/11/2025 (H1N1)pdm09-like virus;

• an A/Darwin/1415/2025 (H3N2)-like virus; and

• a B/Pennsylvania/14/2025 (B/Victoria lineage)-like virus.

The 2026 Southern Hemisphere vaccine already had the recommended updated H1N1 component, but retained the older strains against H3N2 and Influenza B.

Admittedly, seasonal flu is notoriously unpredictable - and a mild epidemic is always possible - but these early signals are worth noting. 

Sadly, seasonal flu vaccine uptake in the United States peaked in 2019, and has registered a slow, but steady decline since.

Pandemic fatigue, plus growing anti-vaccination sentiment, and admittedly `hit-or-miss' protection against influenza infection have all had an impact.  

While I'm not particularly hopeful - with antigenic changes in all 3 flu strains expected to circulate this winter - this would be a good year to see this trend reversed.  

For my part, I'll be rolling up my sleeve later this month, and plan to don face masks when in crowded indoor public spaces and use copious amounts of hand sanitizer.  

At my age, I figure I need every advantage I can get.