A vaccine is a biological preparation which provides active acquired immunity to a particular disease. A vaccine typically contains an agent that resembles a disease-causing microorganism and is often made from weakened (attenuated) or killed forms of the microbe, its toxins or one of its surface proteins. The agent stimulates the body's immune system to recognize the agent as a threat, destroy it and keep a record of it so that the immune system can more easily recognize and destroy any of these microorganisms that it later encounters.
Thus, the correct answer is option A.
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Similar Questions
Q1
____________ is a protein expressed by bacteria or virus on their cell surface.
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Does a vaccine contain only dead or weakened form of bacteria or also a virus?
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If a bacteria or virus reappears, the immune system will recognize them and act faster against them