Every Autumn, I look forward to leaf peeping, impulse-buying decorative gourds, and getting my flu shot. For real. When cozy season starts, I know that a less fun season - flu season - is right around the corner. But, I also know that the flu vaccine is a stellar way of keeping myself, my family, and my community as healthy as possible. As an epidemiologist, I also get excited about all that goes into the flu vaccine, and the journey it takes before it enters my upper arm. This knowledge boosts my confidence in the vaccine, much like the vaccine boosts my immune system. I hope it does the same for you.
All through the year, all over the world, experts monitor which strains of flu are circulating. They then predict which strains will try to steal the infectious disease spotlight during flu season in each hemisphere, and the top four contenders go into the vaccine. This selection process happens months in advance to make sure there’s enough time for production and distribution. In the US, the FDA signs off on the strains around March, and then we’re off to the races...or more accurately, we’re off to the incubator: most flu vaccines in the US start their journey in eggs, with few eggseptions (sorry). Live viruses are injected into chicken eggs, which provide comfy conditions for viral replication. The farm-fresh viruses are harvested, and undergo a process where they’re inactivated (read: killed) and split into smaller chunks of the dead virus. This processing is what makes it impossible to actually get the flu from the vaccine itself (think how difficult it would be for a dead or irreparably weakened mountain lion to attack you - same idea!).
The immune magic really begins when that flu shot enters your arm. Let’s quickly break down what your immune system is building up: all viruses have distinct patterns of proteins on their outer coats (called antigens). When they enter our bodies, our immune system sees them as foreign material that does not belong. The flu vaccine contains some antigens, but not the actual virus, so it tricks the immune system into mounting a response, which includes forming our beloved antibodies. You can think of antigens and antibodies as a lock and a key - each antigen has an exact match to a set of antibodies. When the lock and key meet, the door to the immune response opens - antibodies help recognize the invader virus, attack it, and then flag it for other immune cells to come by and fight it. The process of making antibodies takes about two weeks, so getting the vaccine and producing your antibodies in advance keeps you safe and prepared if you encounter the real virus later in the season. Bear with me a second - you can think of getting the flu vaccine like packing your lunch the night before a school or work day. You don’t need that lunch right then at 8pm, right? But when the time comes the next day, you’ve already done all the prep work. Similarly, getting the flu vaccine is a favor to your future self.
I love learning about diseases, but man, do I dislike getting sick. If I’m exposed to the flu this season, I know that my flu shot will shield me from the worst of its impact, hopefully leaving me totally unscathed or with a mild, manageable case. Even though I’m still working from home, I think about potential exposures to the flu I may have - taking public transportation, seeing friends, gathering for the holidays, to name a few - and who I could also be exposing in those settings, especially those prone to more severe disease, like younger kids and older adults. So join me, find a flu vaccine, and take a shot at protecting yourself and your community this season.