It's Never Too Late to Get a Flu Shot ... Or Is It?

The cheery reminder of “It’s never too late to get that flu shot!” has been popping up on the media lately. Is it correct?

Well… yes and no. From a medical standpoint, it’s true. While an eleventh-hour flu vaccine given to you or your child after influenza has already hit your community won’t protect you as well as if you had received it months ago, it will still give you a measure of protection. How much protection simply depends on the interval between when you got the vaccine and when you personally are finally exposed to the flu. That’s fairly impossible to predict without knowing a lot of other variables. So yes, if you can get a vaccine this late in the season, it is still totally worth doing so. While we are finally experiencing intense flu activity here in Oregon, we haven’t been inundated with it the way the East Coast has, and if you are careful about your exposures and your handwashing, your flu vaccine still has a good chance that it can protect you before flu crosses your path (unless you are a health care worker or a teacher, in which case you have almost certainly been exposed already multiple times).

But there’s a big ‘if’ in that statement. IF you can get a vaccine, it will still help.

Why the ‘if’? Well, it’s January, and many medical offices have either used up their stock of vaccine — and are unable/unlikely to get more — or will soon be running out. As I write this, we still have some vaccine but we aren’t sure how long it will last or how much more we will be able to get. Eventually we too will run out. We might be able to get more, we might not; if we do keep ordering more, we also run the risk that the flu shot frenzy will die down before our supplies run out. That leaves us with unused vaccine, and that’s an expensive proposition.

This article from the FDA is a nice explanation of the science and technology that’s involved in making the flu vaccine every year. I think it’s all rather exciting: the idea of the world’s infectious disease experts getting out their Magic Eight-Balls and making trips to Hong Kong to try to predict which strains will strike us sets my nerdy little heart thumping. I’d love to be a fly on the wall for that. But what the FDA summary doesn’t mention, and what most news stories about flu vaccine leave out, is the rest of the guesswork that’s involved.

How many people will queue up to get the flu vaccine? And when? Will the public flock obediently to their doctors’ offices in early fall, the way we always urge them to? Or, lulled into a sense of false security by a couple of mild flu seasons, will they keep putting it off? If they don’t bother to get the vaccine one year and there isn’t widespread disease, will they be even less likely to bare their arms for a poke the following season?

And when the news media starts showing footage of overwhelmed emergency departments in the big cities, will the public suddenly feel motivated to get vaccinated?

These aren’t questions that can be answered easily by the use of science… at least, not by the kind of science that involves going to the Far East and getting samples from pigs and chickens. Now we’re dealing not with virology and epidemiology, but sociology — human nature — and economics. Human beings, in their own way, are more maddeningly unpredictable than viruses any day.

So after the big brains at the CDC and elsewhere have consulted the stars, tossed the bones, and sacrificed the chickens to study the entrails (okay, not really… after they have Done Their Research) and told the world which strains should be included, then the manufacturers of the vaccine have to make their best predictions of vaccine demand for the coming season. What a lot of people don’t realize is that in this country, the flu vaccine — and routine childhood vaccines — aren’t made by the government, but by for-profit businesses. They want to keep their production of the vaccine high enough to meet the demand, so as not to miss out on sales of vaccine, but they don’t want to overshoot and end up with a lot of unused product. Since the flu vaccine is different every year, leftovers from this season aren’t something that the manufacturers can just keep on ice for next year.

The same process happens on a smaller scale in your doctor’s office. Every year, months in advance, we place our orders. Usually we base the numbers on how much vaccine we were able to give out the previous season. It’s especially complicated for pediatric offices, because there are different vaccine doses for the youngest children versus the older kids. In offices like ours that see both commercially insured kids as well as clients on the Oregon Health Plan, we have to order both from the commercial suppliers and the federal Vaccines for Children program. And then there’s the option of FluMist, the intranasal live vaccine, as well. Somehow, in a process that I don’t even begin to understand, our nursing staff makes their best guess and places the initial orders.

Vaccine usually arrives in late August, and as soon as we have vaccine in all of the necessary categories we put out the call and start vaccinating like crazy. I’m proud of our patients: every year you seem to come in earlier and every year we are able to vaccinate more children (and their parents, when desired) against the flu. It’s wonderful. But it could be better, and this year illustrates exactly why.

Remember the H1N1 influenza epidemic of the 2009-2010 season? That was the year when the novel strain of flu hit first in April 2009, then went underground for a few months only to re-emerge in the fall with a fury that most of us in the healthcare world had never seen before. Usually February is the busiest month of the year for us, but October 2009 broke all previous records for us for the sheer number of patients seen. (Because of what may possible have been the best vacation timing of my career, I ended up spending the very worst week of the season on a working cattle ranch in eastern Idaho; after up to ten hours a day in the saddle for a week a nice flu epidemic back home didn’t sound so bad.) Vaccine production was thrown for a loop and we had two different vaccines to worry about, in addition to all the other variables. First we got the seasonal vaccine the experts had already recommended, then the H1N1-specific vaccine. Or maybe it was the other way around; it’s all a blur now.

Patients packed EDs and office waiting rooms. Lines for the vaccine wrapped around the block. Many offices, including ours, removed toys and books from the waiting rooms and exam rooms to help stop the spread of the flu. Schools closed entirely in some places due to the disease burden. Masks were handed out at the front desk when appropriate. Everyone wanted both the vaccine and antiviral medications if they did get sick. It was, in short, a feeding frenzy, a perfect storm.

We survived, and saw increased interest in the flu vaccine the following year. Everyone remembered H1N1 and most wanted their children to be vaccinated. We had a mild flu season that year, the 2010-2011 season. And the following year, we had another mild season. Memories of the fall of 2009 began to fade.

This year, the country as a whole is having a bad year. Flu is more widespread and more severe and more people are dying from it. The result? Those who didn’t get themselves and their families vaccinated in the fall are now desperately seeking the vaccine. Some are finding it; some aren’t. It’s just so late in the vaccination season.

It might help to think of flu vaccine supplies as being a little bit like breastfeeding. If you’ve breastfed an infant, you know that as the infant feeds for longer periods and more frequently the amount of milk produced increases. It’s supply and demand: baby demands and mama supplies. Baby has a growth spurt and wants to eat every hour? Mama’s milk-producing glands start working extra shifts and paying overtime to get the milk out. It’s the same way with flu vaccine: If we vaccinate like crazy in the early fall and blow through all the doses we’ve ordered by, say, late October, we can order more, no problem. We’ll be able to get more because it’s early in the season and the manufacturers still have stock. If that’s happening everywhere and the manufacturers start to run out, they’ll make more because they know they can still sell it if it’s early in the season. It’s a feedback loop, with more demand creating more supply.

But when demand is lackluster in the fall and then suddenly peaks in January, everyone is caught with their pants down (and not in the sense of waiting expectantly for a shot in the gluteus maximus). Medical offices are reluctant to order more, because no one wants to be stuck with a fridge full of unusable and expensive vaccine. And they might not be able to get more even if they decide to take that risk, as the manufacturers may have called it quits for the season so that they don’t end up with a warehouse of leftovers. This is like the baby who has had a poor appetite for weeks and then suddenly starts eating like crazy; mama’s milk production isn’t going to come back overnight (thankfully, breastfeeding is not a for-profit industry).

The take-home lesson from all of this is predictable, even if the flu virus and the vaccine supply isn’t. Get your flu vaccine every year, for you and your children. Get it early, as soon as the vaccine becomes available. Give your doctor’s office a chance to protect you before the virus hits. The more people we can vaccinate in September and October, the better we are able to get more supplies and vaccinate the folks who will inevitably procrastinate.

Consider it your civic duty.