Can You Please Take Your Flu Vaccine? Thank You.

Can You Please Take Your Flu Vaccine? Thank You.

It’s mid-July here in Perth, and the vibe is, frankly, unwell. If you’re anything like me, your social circle has been decimated by whatever fresh hell this winter’s flu season has decided to unleash upon us. My group chats are a rolling scroll of “sorry, can’t make it, dying” and “WFH, partner is KIA”. It’s a mess.

And it’s not just us. The news is, to use a technical term, figuratively crapping itself. ABC News is calling it ”WA’s worst-ever flu season,” and the nation’s doctors are calling for action as case numbers hit record highs (RACGP, 2025). Over in Queensland, things are so dire they’ve had to halt elective surgeries to deal with the sheer volume of people being hospitalised with the flu.

This all begs the question: Why? What on God’s green earth is going on? Why is the flu, a virus we deal with literally every single year, suddenly acting like it’s on steroids?

Part 1: The Usual Suspects

To understand what’s going on, we first need to meet the cast of characters. When we talk about “the flu,” we’re usually talking about one of three main groups of influenza viruses that like to bother humans.

First, you have Influenza A(H1N1). This is the descendant of the 2009 “swine flu” pandemic virus. It’s a known quantity. It changes, of course—all flu viruses do, in a process called “antigenic drift”—but it does so relatively slowly. This means our annual vaccine, which is basically a highly educated guess about which four flu strains will be dominant, usually has a pretty good bead on A(H1N1). The process isn’t perfect; sometimes the virus changes after we’ve locked in the vaccine strains, and sometimes the process of growing the virus in eggs (which is still how we do it, amazingly) changes it just enough to make our immune response a bit wonky. But generally, we know how to handle this guy.

Next up is Influenza B. These guys are, for lack of a better word, betas. They primarily cause severe disease in children, whose immune systems are still getting the hang of things. Most adults have seen enough Influenza B in their lives that their immune system just swats it away. This contributes to the classic “U-shaped” curve of influenza’s impact, where the very young and the very old suffer the most, while those of us in the middle tend to get off a bit lighter (Leung et al., 2022, doi:10.1093/ije/dyab138).

And then there’s Influenza A(H3N2). This one is a complete and utter bastard. A(H3N2) has an incredibly fast rate of antigenic drift. It’s a master of disguise, changing its coat so quickly that our vaccines can sometimes be rendered almost useless. In seasons where A(H3N2) is dominant, it’s not uncommon to see vaccine effectiveness plummet into the single digits (Xia et al., 2020, doi:10.1111/irv.12772). Historically, when we have a truly terrible flu season, this is the culprit. It’s the strain that puts the fear of God into epidemiologists.

Finally, there’s Untyped Influenza A. This category is almost always along the lines of “Hey we did a RAT test and it said Flu A”. But not which of the A’s. The thing is, this is almost entirely comprised of the other two A strains we’ve talked about, and thanks to statistics being what they are… they’ll be the same proportion approximately as the viruses that are classified. That means if you add up the Known A(H1N1) Cases and the Known A(H3N2) Cases and find that they are split 50/50, you can then assume that the Untyped cases are also split 50/50 between A(H1N1) and A(H3N2).

What’s important there is that only the known cases matter. Oh and B. B we just measure in the aggregate. Anyway.

So, the logical conclusion is that 2025 must be a horror A(H3N2) season, right? It’s the only thing that makes sense.

Let’s look at the data from the latest Australian Respiratory Surveillance Report. This is what’s actually been putting people in the hospital this year.

Source: Adapted from Australian Respiratory Surveillance Report, 13 July 2025

Wait… whaaaaaaat?

The bastard strain, A(H3N2), is having a holiday. The dominant virus is A(H1N1), the one we’re supposed to be good at fighting. So what gives? If it’s not a super-virus, then the problem must be something else. The problem, it turns out, is us.

Part 2: No, Turns Out It’s Because You Won’t Get the Damn Jab

COVID-19 sucks all kinds of ass, for many reasons. One of the big ones is that immunity, whether from infection or vaccination, doesn’t last very long. Your antibody levels fade, and your immune system’s memory of the virus gets hazy. This is precisely why boosters are so important; you need to give your body a controlled, regular reminder of what the enemy looks like so it’s ready for a real fight. If you don’t, your body eventually forgets. And then you get real sick.

Turns out, influenza is very similar.

Your immune system’s memory of influenza, whether it’s A or B, fades over time. If you go a few years without getting infected or getting vaccinated, your body’s ability to fight off the virus is significantly reduced. A long winning streak of not getting the flu means the next time you inevitably do, it’s going to hit you like a freight train, regardless of the strain.

We have a sick hack for this: the annual vaccine! Just like with COVID boosters, the flu shot acts as a yearly training session for your immune system. It keeps that immunological memory sharp and ensures your body is primed and ready to go. This has a brilliant three-pronged effect: it reduces your risk of getting infected in the first place, it reduces the chance of you spreading it to others, and it dramatically reduces how sick you get when you do catch it. It’s a win/win/win.

So, why is this year so bad? Two reasons.

First, the COVID-19 pandemic completely broke the cycle of influenza. Lockdowns, masks, and social distancing didn’t just stop COVID; they nuked the flu from orbit for a couple of years. This created a massive “immunity gap” in the population.

Second, and more critically, vaccine rates have plummeted. According to the latest national surveillance report, influenza vaccine coverage this year, while similar to last year, “remains lower than coverage at the same time in 2023 and 2022” (Australian Respiratory Surveillance Report, 13 July 2025). A combination of pandemic fatigue, a bizarrely popular anti-science sentiment, and general complacency has led to fewer and fewer people getting their annual shot.

This is the perfect storm.

We have a population whose immunity has waned due to a lack of natural exposure, combined with falling vaccination rates. The result is that a completely normal, run-of-the-mill flu strain like A(H1N1) is now tearing through the community and causing unusually severe disease. More people are getting sick, they’re getting sicker than they normally would, and that’s putting an immense strain on our hospitals.

Part 3: How to Fix This?

This is the easiest part of the whole blog post. The solution is stunningly, beautifully simple:

Get the flu shot. Every. Single. Year.

That’s it. That’s the fix.

If we could get a critical mass of people to do this one simple thing, the annual flu season would become a non-event. We’re not going to get to 100%, but every single person who gets vaccinated adds to the wall of community immunity. The more people who are protected, the harder it is for the virus to spread, and the harder it is for it to reach the vulnerable people who can’t get vaccinated or for whom the vaccine is less effective—like babies, the elderly, and the immunocompromised.

So, do your part. Protect yourself, protect your family, and protect your community. Go get jabbed. It literally has only upsides. :)