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Systems for developing and testing vaccines emerged after the 19th century, when many vaccines began to be used. The current system for developing, testing, and regulating vaccines developed during the 20th century as the groups involved standardized their procedures and regulations.
A biological attack may seem more like a plot element in an action film than a realistic threat. Biological attacks, however, have occurred in the past. A collection of U.S. government agencies are involved in planning responses to potential biological attacks.
Vaccines are made using several different processes. They may contain live viruses that have been attenuated (weakened or altered so as not to cause illness); inactivated or killed organisms or viruses; inactivated toxins (for bacterial diseases where toxins generated by the bacteria, and not the bacteria themselves, cause illness); or merely segments of the pathogen (this includes both subunit and conjugate vaccines).
The human immune system is essential for our survival in a world full of potentially dangerous microbes.