This fall, like every other, I tried to game the flu season. My goal, always, is to get my vaccine at just the right moment: before the first cases pop up, yet late enough so that its protective effects last beyond the holidays and well into January or February, when infections tend to peak. That typically means scheduling my appointment for sometime in mid-to-late October.

This year, the virus snuck up on me. Earlier this month, I started hearing from friends with sick kids — weeks before my own teen and I had gotten vaccinated. Drat.

The U.S. is experiencing an unusually early flu season, one that, in another twist, started to pick up steam on the West Coast rather than following its more typical path from southern states north. Not only is that leaving many people unprepared, but early indications suggest it could be another year when our vaccines aren’t an ideal match against the circulating virus.

It’s been a humbling reminder that the flu has a way of thwarting even the best-laid plans.

Infectious disease experts like to say, “You’ve seen one flu season, you’ve seen one season,” says Melissa Stockwell, professor of pediatrics and of population and family health at Columbia University Irving Medical Center. Because it’s so hard to predict when it’ll hit, she recommends skipping my game-the-system strategy and trying to get vaccinated by the end of September or early October.

What’s behind this early takeoff for the flu? Nobody can say for sure, but the virus’s infuriating ability to stay one step ahead of humans could take some of the blame. Influenza is constantly undergoing tiny genetic changes (and in very rare instances, abrupt, major ones) to the pieces of the virus targeted by vaccines. Global health authorities and infectious disease experts closely track those shifts with the goal of choosing the most protective composition for annual vaccines.

It's hard to get that recipe exactly right. The World Health Organization’s flu team typically picks the strains in February so that vaccine manufacturers can have the shots ready for the fall — a long enough lag for the flu to surprise us. The world was reminded of the challenge last year, when a new strain called subclade K, a mutant of H3N2, was able to circumvent both the flu shot and our preexisting immunity (protection acquired from past infections and vaccinations).

This year, preliminary evidence suggests the culprit behind the West Coast’s unexpectedly early flu cases is a mutation in H1N1 called G155E, says Alex Greninger, a virologist who leads infectious disease diagnostics at the University of Washington. Some 80% of the patient samples sequenced by Greninger’s lab in August and September carried the mutation, which he says was also prevalent in cases during flu season in the Southern Hemisphere and Southeast Asia.

To be clear, existing vaccines, while not a perfect match, are still worthwhile. Last year’s shots offer a good case for that: though subclade K rendered them less effective than in prior years, they still lowered the risk of doctors’ visits and hospitalizations for the flu. And they seemed to work best at protecting kids, who in recent years have been hit hard by the virus.

So even though the G155E mutation isn’t present in this fall’s flu shots, lab studies suggest the vaccines should still offer some level of protection. Moreover, anyone who didn’t get the flu last year will want the updated shot, as it protects against subclade K, which is still hanging around, as well as against influenza B, a strain that tends to circulate later in the season.

Another piece of good news: We’re moving closer to a world where flu shots can be better matched to the circulating virus. In August, the Food and Drug Administration approved Moderna’s flu vaccine for older adults, making it the first mRNA-based shot against the virus to reach the market. Studies suggest the technology can elicit a broader and longer-lasting antibody response than conventional shots, and it takes far less time to manufacture. That in theory suggests a future where the vaccine composition could be chosen much closer to the actual flu season.

For now, though, anyone feeling behind on the crucial task of getting their flu vaccine should take some comfort in the fact that there are more options out there than ever before — whether that’s conventional shots, Moderna’s mRNA-based product, or even an intranasal spray that this year can be mailed directly to the majority of Americans.

And remember that there are no bad choices — so long as you follow through and get vaccinated.

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This column reflects the personal views of the author and does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.

Lisa Jarvis is a Bloomberg Opinion columnist covering biotech, health care and the pharmaceutical industry. Previously, she was executive editor of Chemical & Engineering News.

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