Since flu is something we have almost all had and usually survive, people probably underestimate the potential seriousness of the flu. However, flu and flu related complications (especially pneumonia) are estimated to be the
the 7th leading cause of death in the U.S. Illness due to flu accounts for about 200,000 hospitalizations and about 40,000 deaths each year. Of those deaths, about 90% are 65 and older and most of the rest are in infants. However, there can be devastating outbreaks of the flu. In 1918, the flu killed 10's of millions of people world wide. The 1918 epidemic was unusual in that most of the deaths occurred in relatively young adults. However, most years the vast majority of flu related deaths are in those 65+. I note that the 65+ demographic is well represented on the C-Brats.
Unlike bacteria for which we have good antibiotics (at least at present), the drugs to treat the flu are only moderately effective. Hence vaccination which prevents infection or limits the extent of infection is perhaps more important for the flu than for other infectious agents. The vaccine is estimated the reduce the likelihood of flu related incidents by about a factor of two but the effectiveness varies from year to year depending on how well matched the vaccine is to the viruses that are circulating (see
this link and references therein for vaccine effectiveness studies).
Flu viruses in nature rapidly mutate and recombine (e.g. exchange genetic material) with other flu viruses. The natural reservoir for the flu virus is in birds - e.g. birds, both wild and domesticated carry the flu virus. Overtime, the flu viruses that are circulating in the population mutate into new forms. Hence, a different vaccine is made each year in an attempt to "match" the vaccine proteins to those of the virus that is most likely to be circulating in the population. Vaccines work by introducing viral proteins into you body so that your own immune system builds up more antibodies and T-cells of a type that make it easier and faster for your immune system to recognize a viral infection. Since, we cannot accurately predict exactly which flu viruses are circulating in the population in a given year, the vaccines that are produced represent the best guess as to what will be present during "flu season". Some years the guess is better than others and the vaccine is highly effective, some years it is not.
In the past, the only method we had to make flu vaccines was by culturing (growing) isolated virus in chicken eggs (we don't have other good methods for culturing flu virus in large amounts). With this technology, it takes a long time to produce enough vaccine for the population and hence it's difficult to rapidly change the vaccine to match the flu virus is currently circulating. However, the advent of a number of new technologies (DNA cloning, commercial DNA synthesis, rapid sequencing of flu viruses) has made it possible to manufacture proteins from the flu virus without growing a live virus in chicken eggs. With these newer methods, it is now possible to more rapidly manufacture vaccines that will better match the virus. However, it's a long process to get new methods and vaccines approved through the FDA so it will likely be a few years before we see these engineered vaccines completely replace the chicken egg method of production. See
this link for more on how the flu vaccine is made.
The primary adverse reactions to the flu vaccine
"include soreness, redness, or swelling where the shot was given, fainting (mainly adolescents), headache, muscle aches, fever, and nausea. If these problems occur, they usually begin soon after the shot and last 1-2 days.". Some of these types of reactions (especially fever and swelling) are the natural result of your immune system doing what it is supposed to do - e.g. building up the systems necessary to fight off the real flu virus. One thing to consider/remember is that while you may have gotten sick shortly after receiving a flu shot, the fact that the two events were near each other in time doesn't indicate that the vaccine itself caused the illness. E.g. any given individual get's sick every so often so some subset of the individual who get the flu vaccine will get sick shortly thereafter for other reasons. Hence those who study adverse reactions from the vaccine (or indeed any other medication) have to look at fairly large groups of people to determine if those who were vaccinated got sick at a higher rate than those who were not. Such studies are part of any vaccine or drug trial and for vaccines, the results are generally unambiguous. E.g. the benefits of the flu vaccine outweigh the risk of illness that might be caused by the vaccine. Because the vaccines are still mostly manufactured in chicken eggs, some egg proteins are present in the vaccine. For those with severe allergies to eggs, the vaccine can cause an allergic reaction. Such cases are pretty rare but if you know you have an allergy to eggs, you should avoid all vaccines produced in eggs. In the future, recombinant DNA techniques will prevent these types of allergic reactions.
Some have expressed the concern that the government or a given place of employment (e.g. a hospital) asks or requires people to vaccinate themselves against a variety of infectious agents. For this concern it's important to understand that vaccinations work best when a large fraction of the population is vaccinated/immune to a given infectious agent. That is any virus or pathogenic bacterium needs a host in which to live. Transmission of the virus from one person to another requires that both people can host the virus. Those with immunity (or partial immunity) will not host the virus (or will produce much lower levels). When there are enough of these people in the population, transmission of the virus is reduced or eliminated. When only a small percentage have immunity, there's very little effect on transmission. Hence, vaccination not only protects yourself but also protects the community around you. With vaccination, our own actions have impact on the health and well being of others, and that's the rationale for government and employers (the military, health care facilities etc) to encourage and in some cases require vaccinations. It's also why I consider keeping my own vaccinations up to date a moral obligation to my community. Those of us with grandchildren who visit frequently or those who are frequent visitors to a friend in a hospital or nursing facility might want to consider the benefit of our actions in protecting these more vulnerable populations. If you don't believe that vaccination rates affect community health, you might want to look at a recent
study that shows that outbreaks of whooping cough (often deadly) are 2.5 times higher in communities with lower vaccination rates.
As an aside, much of what is in a Miles post above (a few above) was copied and pasted from
Joseph Mercola's web site. While Mercola does have a wide following on both his web site and on others, his medical advice is not held in high regard by many in the field. If you're interested, do a google search using the terms (Joseph Mercola quack or Joseph Mercola FDA warnings), see what turns up and draw your own conclusions. Or if you're in a hurry, take a look at the
Wikipedia article on Mercola.
