Dear Gentle Reader,

Travelling back to New Zealand from the UK had its consequences this time - a bout of flu that hit like a sledgehammer and effectively put me out of action for 2 weeks. I’m sure in my younger days I would have returned, grizzling, back to work after 72 hours, but the advantage of getting older and more bedridden is that I was less likely to contribute to the epidemic as well as annoying my colleagues far less with my self-pitying tones. I made the rational (?) decision to leave my phone in the office which was about 15 steps too far for this particular hypochondriac.

It seems there were many of us who were surprised by the severity of this year’s flu (anecdotal evidence mainly); getting one's energy back and losing the residual aches and pains seemed to take much longer. Probably just old age. Ah well…

Hoping you are healthy and safe;

Ruth

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When the flu isn't just the flu

While we can predict the occurrence of influenza each year, it’s pretty challenging to predict how severely it will hit the healthcare system. Unfortunately, this year that test has been quite visible in the Southern Hemisphere with record rates of respiratory infection hospitalisations.

For healthcare services, the consequences were substantial. Patients faced lengthy waits and corridor care, while some elective procedures were cancelled to free up resources. Healthline calls also rose above levels seen at the same point in the previous three years. Children aged under five and adults aged 65 and over were among the groups experiencing the highest hospitalisation burden.

Influenza places pressure on the entire system. More infections mean more GP consultations, emergency department visits, diagnostic testing, prescriptions and, for the most seriously affected patients, hospital admissions.

Additionally, healthcare workers are human and catch influenza too. Demand can therefore rise at precisely the same time as staff sickness reduces capacity.

Influenza is not a new pathogen or an unexpected public health emergency. We know winter will bring increased respiratory illness. What we cannot know with the same certainty is how severe each season will be, or how much spare capacity will be available when it arrives.

The distinction between an ordinary case of influenza and one requiring hospital care is not simply a matter of symptom intensity. WHO classifies influenza broadly as non-severe or severe. Most uncomplicated infections fall into the first group and resolve without hospital treatment. Severe influenza includes complications such as pneumonia, sepsis, acute respiratory distress syndrome or deterioration of an existing medical condition. Clinicians must also consider whether someone with apparently uncomplicated influenza has characteristics that make progression to severe disease more likely.

During a period of widespread influenza circulation, an otherwise well patient with a characteristic illness may not require laboratory confirmation at all. In severe illness, however, identifying the virus becomes considerably more important. Molecular tests such as PCR can confirm influenza and help inform antiviral treatment and infection-control decisions, while investigations such as oxygen measurement and chest imaging help identify complications rather than the virus itself.

Pneumonia is one of the points at which the clinical problem changes substantially. Influenza can directly cause viral pneumonia, while secondary bacterial pneumonia can develop during or after the initial infection. What began as a familiar seasonal respiratory illness can therefore move from self-care or primary care into a much more resource-intensive pathway involving diagnostic testing, imaging, oxygen therapy and hospital admission.

The knock-on effect

The pressure created by a severe flu season affects far more than the patients who have influenza. A hospital bed occupied by someone with serious respiratory illness is a bed that cannot be used elsewhere. Staff redirected to meet acute demand are no longer available for other services. When emergency departments become busier and inpatient capacity tightens, elective procedures may be postponed and waiting lists can grow.

During the hospitalisation surge in NZ in August 2026, 188 elective surgeries were cancelled in Auckland to free up resources. Elsewhere, patients reported waits of more than 17 hours in emergency departments.

Primary care feels the effects too. An influx of patients with respiratory symptoms competes for appointments with people requiring management of cancer, cardiovascular disease, diabetes and other acute and chronic conditions. Add staff illness to the equation and capacity can tighten further.

When we talk about advances in medicine we’re often focusing on what new treatments or technologies are being developed, yet that is only one part of improving patient outcomes. Patients also need a healthcare system with the people, infrastructure and capacity to diagnose them, prescribe that treatment, monitor them and provide follow-up care. A highly effective new treatment is almost rather useless if the system delivering it to patients cannot keep up with demand.

Winter here. A warning elsewhere?

For our readers in the Northern Hemisphere, winter may feel a long way away. However, influenza surveillance is an international affair.

Countries around the world continuously contribute virological and epidemiological information to the World Health Organization's Global Influenza Surveillance and Response System (GISRS), which currently includes 166 institutions across 136 WHO Member States. The system monitors which influenza viruses are circulating and how the disease is behaving globally.

That surveillance also contributes to decisions about future vaccines. WHO reviews global surveillance data and makes influenza vaccine-composition recommendations twice each year: in February for the Northern Hemisphere and September for the Southern Hemisphere.

This year's predominant influenza strain in New Zealand has been A/H3, with sequenced sentinel samples identified as subclade K. The same subclade had already caused considerable influenza activity during the preceding Northern Hemisphere winter.

Influenza viruses continue to evolve, and global surveillance draws on evidence from many countries. But what happens during the Southern Hemisphere winter forms part of an international picture that helps health authorities understand how influenza is changing and prepare for what may come next.

Can we prepare for predictable pressure?

The challenge with influenza is that we know it is coming, but we do not know exactly what it will bring.

Surveillance can tell us which viruses are circulating and identify changes in influenza activity. Vaccination can reduce the risk of severe disease. Health services can plan staffing, bed capacity, diagnostics and medicines ahead of winter. Public communication can help people understand vaccination, self-care and when they need medical attention. But being properly prepared is nearly impossible when a seasonal surge arrives in a system already operating close to capacity.

This issue extends well beyond influenza. COVID-19, RSV, extreme weather events, workforce shortages and unexpected outbreaks can all produce sudden increases in demand. A health system designed around normal activity needs enough flexibility to cope when normal temporarily disappears.

Perhaps the lesson from a difficult flu season is therefore less about influenza itself and more about the value of spare capacity. Efficiency matters in healthcare, but so does resilience. A system with no room to absorb additional demand can quickly find a predictable seasonal illness becoming a much broader healthcare problem.

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Flu season arrives every year. Its severity does not follow such a convenient schedule.

We cannot build a health system that anticipates every eventuality, but we can recognise that periods of unusually high demand are not unusual at all. The challenge is ensuring that caring for one surge of patients does not compromise our ability to care for everyone else.

The timing of flu season is broadly predictable. Its severity isn't. Resilient health systems need enough flexibility to accommodate both.

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