Why the Flu Vaccine Doesnt Work All the Time

The Centers for Disease Control (CDC) is looking at whether or not the flu vaccine is effective. Preliminary results indicate youll get just as sick (with colds, flu, flu-like illnesses) if you got the vaccine than if you didnt. Why doesnt the vaccine work? In order to understand the answer, youll need to understand some specifics about the flu vaccine and a bit about how immunity works. Flu Vaccine Facts There is no single virus that causes the flu; there is no one flu vaccine that protects against all of them. A flu vaccine is designed to confer immunity against the strains of flu that are expected to be most common and most serious. The vaccine is a sort of one-size-fits-all solution, even though there are more types of flu than covered by the vaccine and the flu types vary according to a region. It takes time to produce vaccines, so a new vaccine cant be instantly produced when a new type of flu starts to cause problems. The Vaccine and Immunity The flu vaccine gives your body parts of inactivated flu viruses. These virus parts correspond to parts of proteins floating around in your body. When the virus part contacts a chemical match, it stimulates the body to produce the cells and antibodies that can remove this particular intruder. Antibodies are proteins that float in body fluids and can bind to specific chemical markers. When an antibody binds to a substance, it essentially marks it for destruction by other cells. However, an antibody for one type of flu wont necessarily bind to a virus part from another type of flu. You dont get protection against other viruses. A flu vaccine can only stimulate your immune system to protect you against the viruses in the vaccine, with some lesser protection against very similar ones. Incomplete Protection Against Intended Targets You may not even get protection against the intended virus. Why? First, because viruses change over time. The piece that was in the vaccine may not look the same (chemically) as the real thing (months later, after all!). Second, the vaccine may not have given you enough stimulation to fight off the disease. Lets review whats happened so far: the inactivated virus piece has found a chemical match in your body. This causes an immune response, so your body has started to gear up its production of antibodies and similar markers on cells that can mark the virus for destruction or kill it outright. Its like calling up an army for a battle. Will your body win the fight when the real virus comes to call? Yes, if you have enough defenses built up. However, you will still get the flu if: Your body isnt fast enough producing a response.Get the vaccine and get exposed to the flu too soon (less than 2 weeks).Too much time between vaccination and exposure (the vaccine loses its effectiveness over time).You dont produce enough of a response.Overwhelmed by exposure to a high level of the virus.Your body couldnt recognize the initial virus piece (this determined by genetics).Your body didnt make enough antibodies/cells (this is common in older people or people with suppressed immune systems).The virus as changed beyond your bodys ability to recognize it.The part of the virus that was in the vaccine cant be detected by the body in the intact virus. But Is It Actually a Waste of Time? Yes and no... the flu vaccine will be more effective some years than others. The CDC predicted that the vaccine developed for the winter of 2003/2004 wasnt going to be effective against most cases of the flu because the strains covered by the vaccine werent the same as the strains that were common. Highly targeted vaccines work, but only against their targets! Theres no point in accepting the risks of a vaccine for a disease you cant get. When the flu vaccine is on-target, its more effective. Even then, the vaccine isnt perfect because it uses inactivated virus. Is that bad? No. A live vaccine is more effective, but much more risky. Bottom line The flu vaccine varies in effectiveness from year-to-year. Even in a best-case scenario, it wont always protect against the flu. The CDC study didnt say that the vaccine didnt work; it says the vaccine didnt protect people from getting sick. Even with imperfect effectiveness, the vaccine is indicated for certain people. In my opinion, however, the vaccine isnt for everyone and certainly shouldnt be required for otherwise healthy people.