Vaccines have been developed against influenza, pneumonia and some allergies. Thus far, efforts to produce a cold vaccine have been unsuccessful although scientists claim to have identified a relatively stable part of the cold virus's outer coat against which a vaccine may one day be developed.
By identifying the types and variants of influenza virus, scientists have developed an effective vaccine. But since the virus changes its antigen every year, immunity seldom lasts for more than twelve months. At present, the vaccine is also effective against only a single variant of the disease (a statement subject to future change).
Since influenza vaccine must be produced months in advance, and no one knows exactly which variant will predominate next winter, predicting which vaccine to manufacture is an inexact science. The U.S. Centers for Disease Control (CDC) continually monitor new flu mutations throughout the world. Each spring, CDC representatives meet with influenza advisory committees to try to determine which strain of virus to include in next season's vaccine.
Despite this pooling of experience, they can still be wide of the mark. When the swine flu appeared in 1976 its generic make-up closely resembled that of the Spanish flu that caused the worldwide epidemic of 1918. The U.S. Government prepared to vaccinate all Americans against what seemed like a particularly virulent rogue virus. But it all turned out to be a false alarm and some people who received the vaccine experienced neurological problems.
Nor is flu vaccine entirely free of side effects. Between four and twelve percent of recipients have experienced mild flu symptoms for twenty four hours after injections. More rarely, people who are sensitive to eggs may develop a serious allergic reaction. Many people also experience pain and tenderness at the inoculation site.
Most vaccine in use today is bivalent, implying that it is effective against a variant of either A or B types. However, significant protection seldom lasts longer than six months and a person is still only immune to the mainstream variant Inoculation provides little immunity should a new subtype appear. And some researchers believe that vaccines tend only to serve to help promote evolution of new flu virus strains.
If you do decide to be vaccinated against flu, remember that it takes some fourteen days for the immune system to produce antibodies in response to the injection. For maximum protection, you should be vaccinated by mid-October.
The prescription drug Amatadine is also used to prevent Type A influenza in high risk populations. It can be taken up to two days after symptoms appear. However, Amatadine may cause side effects ranging from poor concentration to mild headaches, insomnia or irritability.
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