Right now we are in the middle of the flu season, so I thought I’d spend some time this season writing about the flu and other winter illnesses. Can you get the flu from the flu shot? is a common question. Although I am not a proponent of mandatory vaccinations of any kind, and I have reservations about several facets of the manufacturing process and safety of some vaccines, I do think it is smart to get a flu vaccination.
As a nurse, whenever I recommend this to someone, inevitably a few will tell me that they refuse to get vaccinated, for the flu, because
they are afraid it will give them the flu.THE FLU SHOT CANNOT GIVE YOU THE FLU!!! “but I’ve gotten the flu previously, right after I had the shot”, they tell me, or they know someone who has.
There are several reasons for this seeming phenomena, but none of them are because the flu shot caused the person to get the flu.
Here are some of the reasons a person could get the flu after getting a flu shot:
- The shot didn’t have enough time to work. Flu shots work by injecting a small amount of the Killed influenza virus into the persons body. The body then recognizes the virus and makes antibodies against it. Theses antibodies circulate within the persons immune system for a period of time. If the body then encounters the influenza virus during the time these antibodies are circulating, they fight off and kill the virus before it has enough time to multiply and make the person sick. It takes time for the body to make enough of these antibodies. If the person contracts the flu virus before enough of the antibodies are made, the person can get sick. It takes a full 2 weeks for the body to produce enough antibodies to make it possible to kill off the flu virus, and can take up to 6 weeks to be fully effective. This is why we should all get our flu vaccinations at the very start of the flu season, or even a few weeks beforehand.
- The person could have been exposed to the flu before they even received the flu shot. According to the CDC (Center for Disease Control), the influenza virus has an incubation period of 1-4 days, with an average of 2 days. This means that you probably won’t experience any symptoms or have any clue that you have the flu virus replicating inside of you, until 1-4 days after you’ve caught it. In fact, a person is most contagious, and therefore more likely to spread the flu to others, during the day or two just prior to feeling sick. This is why it is so easy to spread. We give it to, and catch it from others, before there are any symptoms present. Add to that the locations where people generally receive the vaccine: doctors offices, clinics, and drug stores, (where sick people tend to be), and it is very easy to see how this can happen.
- They have been exposed to a different strain of the flu virus. Every year, scientists try to determine the most likely strains of the flu that we will encounter. There are 3 main types of the influenza virus, types A, B, & C, These can further be broken down into subcategories of these types, with many different combinations. Although there is a science behind the determination, it is still kind of a crap-shoot as to whether the vaccine made for a given year will be for the exact type of flu virus that surfaces during that season. People who travel are at a higher risk for this problem, because different types of the virus, or mutations of them, may be more prevalent in other areas, and we tend to have more natural immunity to what is local to us. Even so, there is some cross immunity among the different types of the virus. A vaccine for one type will still give some protection against the others, and if the flu virus is still caught, the symptoms are usually not as bad, and/or the illness usually does not last as long.
- They have a similar illness that is not the flu. Many different illness are spread around during the flu season, such as colds, pneumonia, stomach flu, and other stomach viruses, (what people usually call the stomach flu is actually not the flu virus at all. The flu is a respiratory virus. Although nausea and vomiting may occur with it, this is usually due to the fever that results from the flu). A flu shot is only effective against the influenza virus and not other viruses and bacteria that can make us ill.
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