A child is given a vaccine against measles. Which sequence BEST describes how the vaccine protects the child?
AThe vaccine makes the child immune to all viral diseases at once
BThe vaccine kills any measles virus already present in the child
CThe vaccine releases antibiotics inside the body that destroy the virus
DDead/weakened microbes are introduced; the body produces antibodies and remembers how to fight the real microbe if it enters later
Answer & Solution
Correct answer: D. Dead/weakened microbes are introduced; the body produces antibodies and remembers how to fight the real microbe if it enters later
A vaccine contains dead or weakened microbes. The body's immune system practises on them by producing matching antibodies. Even after the practice microbes are cleared, the immune 'memory' remains, so a future infection by the real microbe is neutralised quickly.
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