I Got Vaccinated as a Kid, Why Do I Need to Take the Flu Vaccine Every Year?
This is a question that comes up a lot, and it’s a totally valid question. It doesn’t really make sense to ask people to take a vaccine yearly for something they already got. You aren’t asked to get your Measles vaccine another time after childhood. So what is going on in the doctor’s office? Are they just trying to just charge you for nothing?
Absolutely not.
The reason is that certain diseases may require more than one dose of a vaccine for a variety of reasons. Most infections that we get vaccinated for come in the form of viruses or bacteria. Normally, a vaccine is able to take a small part of the organism and inject it into you in a safe way. This makes it easy for your body to recognize the foreign bug and fight it sooner. This way the bug never gets a chance to multiply in your body and make you feel really sick.
But the flu virus is a little bit different. The flu virus, among a few other viruses, has a special ability that microbiologists call “Reassortment”.
With this ability, the flu virus is able to mix around the genes it has with other flu viruses. Here’s an example:
Think of a virus like a dog. Dogs have different breeds. Retrievers, Beagles, German Shepherds, etc.
Similarly, the flu virus, like most other viruses, has different “breeds” that we call strains.
When a golden retriever and a poodle have a puppy it’s an adorable Goldendoodle. A totally new breed that came from its parents. Viruses on the other hand can’t reproduce per se, but two different strains can infect the same cell. This could easily happen in flu season when lots of people have the flu and pass it along to others. One unlucky person may get both strains from public places like the library, gym, office etc. Then, when both strains are inside a cell, they can incidentally mix up their genetic code and be totally fine. This is the ability called “Reassortment” that we talked about. Now this new strain can go out into the world when that unlucky person sneezes, coughs or somehow contacts somebody else.
This sort of scenario happens constantly and it ramps up a lot every winter — the flu season. The flu vaccine from the year before is based on the older strains of the virus and might not be effective against the new ones. “MIGHT” because there’s no way to account for every single person that will get infected with the flu in any given year. It’s impossible to predict the future of course. But what scientists can do is take samples of the most commonly spread strains from the previous year and work out a vaccine that can protect against those. That way the vaccine can help protect against the newest strain that may or may not come out. The effectiveness of the vaccine varies year and year. That doesn’t mean you shouldn’t get it. Remember, even a poorly effective vaccine is still a little bit of protection and you’ll still be way better off than having no protection. Next time you go to get your flu shot you’ll hopefully understand why they come out with one every year.
DISCLAIMER: This article is for educational purposes only. This should not replace the speciality or counselling of your physician.
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