Vaccines
Vaccines work by introducing biological materials into the body to produce specific immunities. They are most effective when introduced several months before encountering microbes in a real-world setting. For instance, the influenza vaccine introduces biological flu materials into the body so that the immune system may translate the code learned to fight the vaccine material into creating antibodies to fight the new flu microbes.
Determining Flu Strains
The flu vaccine is a recombinant vaccine (proteins placed into mediums such as yeast and E. coli) derived from various strains of influenza. The body creates specific antibodies for each flu antigen (the biological material that creates the body's immune response), and for this reason correct identification of the strain is critical in the creation of a working vaccine. The flu virus changes as it spreads over the globe, adding another problematic element to vaccine manufacturing. Nine months are required, on average, to identify and create a flu vaccine and test the formula to determine dosage requirements. Even with such preparation, the vaccine occasionally does not match strains properly with the flu infection itself, and so researchers will identify two to four strains to be included in each new vaccine formula.
Live Vaccine
There are currently two types of live vaccines. The first, the live attenuated vaccine, takes DNA from the virus so that the infection is less severe. The subunit vaccine uses only a part (or unit) of the flu virus. Live vaccines are created by selecting a flu strain cell, placing it in a culture that promotes growth, maintaining the culture for an average of 22 to 96 hours, washing and then harvesting the cells. The exact time for the growth cannot be predicted, according to the CDC. The final step in creating the live virus is to cool the scraped culture and include the additives, such as the preservative sodium benzoate. The host for the medium includes chicken eggs or large, industrial, sterilized vats.
Killed Vaccine
The term "killed" vaccine is used to describe a live vaccine that has been killed. The killed virus is sometimes called a "dead" or "inactivated" vaccine. Killed vaccines are manufactured in the same manner as a live vaccine except that the final step involves exposing live cells to a strong chemical, such as formaldehyde, to kill it. The body still produces antibodies in reaction to exposure to the killed cells. This vaccine takes much longer to produce than the live vaccine.
Cell-Culture Method
The Journal of the American Medical Association in 2007 reported a new, experimental vaccine production using caterpillars. The DNA vaccines take genetic material from the worm virus and replace it with human flu virus genes. The worm then manufactures additional human flu virus antibodies. Dr. John Treanor states that this new process takes approximately a month less to manufacture the virus, and it does not expose workers to a live flu virus. This vaccine may be used for people allergic to eggs, which is another advantage. The cell-culture method process, protected under a proprietary manufacturing license, is still considered experimental at this time.
