Every year, rumors circulate concerning the flu shot, and muddy the waters for patients trying to make an educated decision about the vaccine. Here, I will discuss some common beliefs about the flu vaccine in order to clear up the confusion and help answer your questions.
FACT – You should receive a flu shot every year. Unlike most traditional viruses we receive vaccines against, influenza is a tricky bug. In order to survive (and by survive, I mean infect as many people as possible) the virus mutates regularly so that our immune systems are fooled and unable to recognize the flu virus for what it is. While the circulating immunity in your body from last year’s vaccine still exists, those antibodies will not recognize the new « improved » version of the virus after it mutates. The CDC tracks these mutations as the flu spreads over the world each year, and formulates each year’s new vaccine against these tracked mutations. In short, you need a vaccine every year in order to be protected from the current circulating virus.
FICTION – You can get the flu from the flu shot. Everyone has heard the story of the person who had never had the flu before until the year they got the flu shot, and then they got sick. There are a few reasons why this rumor exists, and I will cover them here. Before I do, let me say firmly and finally that it is not possible to get influenza from the flu vaccine. Period. The End. So why does this rumor persist ? Let me explain….
Situation 1) The flu is spreading like wildfire, and people are dropping like flies. Joe Shmo, who has never gotten a flu shot in his life, watches this on the news and thinks – « I should probably get my shot this year if things are this bad ». So he goes to his pharmacy and gets the vaccine. A week later he is sick in bed with the flu – clearly from the shot, right ? Wrong. The vaccine takes a full 2 weeks to create an immune response in the body. When you wait until the flu is already spreading in your area, it’s likely that you have already been exposed before you decide to get vaccinated. Which means the vaccine is too late to protect you, as you were already incubating the virus before you got it.
Situation 2) You get your flu shot at the end of August, well before flu activity starts in your area. The next day, your arm is sore, you have a headache, and feel lousy – like you are getting sick. Clearly, the shot gave you the flu, right ? Wrong. What is happening here is a normal immune response to a vaccine. Keep in mind that the way vaccines work is to show the body pieces of dead flu virus. The body recognizes them as bad, and starts creating antibodies to fight them off. Then, when the real live virus infects you later, the body now has a fully developed arsenal of antibodies to fight it with, and you don’t get sick. The run down, icky feeling you have for a couple of days after the vaccine is the body learning to recognize and fight the virus – in other words, a normal mild immune response. It’s usually very mild, only lasts a day or two, and it isn’t the flu.
Situation 3) You get the shot in August. You get sick in October. The shot made you sick, right ? Wrong. This is probably the most common misunderstanding of the flu vaccine. First of all, it’s a guess as to which flu virus will circulate each year, so sometimes the virus mutates in a way no one expected, and you end up getting the flu because the vaccine you received wasn’t for the right strain. Also, it could be that your illness is a cold, or any of the other viruses that cause symptoms similar to influenza (which is why they are called ILIs, or Influenza-like Illnesses). Again, the virus can’t protect from every illness circulating all winter, so you may still get sick and it has nothing to do with the flu or the vaccine.
FICTION – Flu shots contain poisonous levels of mercury. Yes, some flu vaccinations use trace amounts of a mercury derivative, known as thimerosal, as a preservative to prevent the growth of harmful bacteria in the vaccine. No, these levels are not toxic. To put it in perspective, a tuna sandwich has 5 times more mercury than 1 dose of flu vaccine, and a breastfed baby gets 25 times more mercury from breast milk in 6 months than what is in 1 dose of flu vaccine. The type of mercury found in vaccines is not the kind that has been shown to be an issue. The type that has been shown to cause problems is called Methyl mercury. This is NOT the type of mercury in vaccines which is called Ethyl mercury. Ethyl mercury in vaccines is a larger molecule that cannot cross the blood-brain barrier to enter the brain.
I hope I’ve answered some of your common questions about the flu vaccine – feel free to ask more in the comments and I will address those as well !
Until next time….