Is it too late to get a flu vaccine this season?

No. Queensland's free flu vaccination program runs until September 30. Even with case numbers rising now, a vaccine administered this month provides meaningful protection for the remaining weeks of the season and into early spring. The 2–3 week lag between vaccination and peak immunity means sooner is better, but later is not pointless.

I got vaccinated in March — am I still protected?

Vaccine-induced immunity wanes over time. If you were vaccinated in March or April, your protection is now approximately five to six months old. Immunity against influenza typically begins declining from around four to six months post-vaccination. Whether your immunity is still clinically meaningful depends on the degree of match between the vaccine strains and circulating strains this season — something your GP can discuss with you in the context of your overall health.

Queensland flu is still rising — and your vaccine may be fading

What just happened

Queensland Health has reported a significant late-season influenza surge, with 2,930 cases recorded in the most recent reporting week — a 27% increase from the week prior, following an even steeper 44% jump the week before that. Year-to-date, Queensland has recorded more than 20,800 cases, which is actually 69% lower than the 67,000 cases at the same point last year — but the upward trajectory is the concern, not the annual total.

Between August 17 and 30, 294 Queenslanders were admitted to hospital with influenza. Cases are most concentrated in metropolitan hospital and health service areas, though the surge is affecting multiple regions across the state.

What makes this pattern unusual is the timing. Queensland flu season has historically peaked between June and August. This year’s surge began in mid-July after abnormally suppressed numbers through early winter — and is now accelerating as spring approaches. Dr Lara Herrero, virology and infectious disease expert at Griffith University, described this as “probably the latest season we’ve had in the past five years.”

The both-and

Why waning immunity matters — right now

The mechanism behind the late-season surge is not a mystery. As Dr Herrero explained: “the more distance we are in time from our flu vaccine, the greater the chance that our immunity will start waning.” Most Queenslanders who were vaccinated this year received their flu vaccine between February and May. That means immunity is now five to seven months old — and for influenza, that is meaningful.

Vaccine-induced immunity against influenza does not drop off a cliff, but it does decline progressively. The practical consequence is that the people most likely to be in the at-risk zone — those vaccinated early in the year, particularly older adults, people with chronic illness, and those who are immunocompromised — are now facing a rising case count with reduced protection at precisely the moment they expected to be safely past flu season.

This is not a vaccine failure. It is the predictable interaction between a seasonal immunisation program, waning immunity timelines, and a season that started late.

The program timing problem

Queensland’s free flu vaccination program ends September 30 — and the surge is still accelerating. Dr Herrero noted it was “a shame” that the program concludes at the point when supply constraints could most affect how the peak progresses. This is a structural problem: vaccination program timelines are designed around typical season patterns, which this year has not followed.

The complexity for public health communication is real. Telling people to “get vaccinated” is easy. Telling people who received a vaccine six months ago that it may not be sufficient for the current season — and that they should consider revaccination — is a different, harder conversation. Whether a second dose in the same season is clinically justified for specific high-risk groups is a question to discuss with your GP, not a blanket recommendation for everyone.

What is not complex: if you have not been vaccinated this year, now is a good time.

My two cents

Late-season flu surges carry a particular risk that mid-winter peaks do not: people have stopped thinking about it. The psychological flu season ends when winter does, approximately when people put their jumpers away. The virus does not get that memo.

The practical message for this week is simple. Queensland’s free vaccination program runs until September 30. If you are unvaccinated this year, or if you were vaccinated early in the year and fall into a higher-risk group — older adult, pregnant, chronic respiratory or cardiac disease, immunocompromised — it is worth a conversation with your GP about whether a booster is appropriate for you this season.

Beyond vaccination: hand hygiene, staying home when unwell, and wearing a mask if you have respiratory symptoms are still the most reliable non-pharmacological tools. These have not changed. They work at any point in the season.

Verdict: yes — actionable now, with a clear deadline: Queensland’s free program ends September 30.

Sources cited

Experts warn of late-season uptick in influenza — ABC News, September 2026. https://www.abc.net.au/news/2026-09-04/queensland-influenza-case-uptick-vaccination-summer/107111540
Queensland Health — influenza surveillance. https://www.health.qld.gov.au/clinical-practice/guidelines-procedures/diseases-infection/surveillance/respiratory