Vaccines are a kind of immune-insurance policy. Although the body comes stocked with millions of different antibodies, there is always the chance that the one you need won't be available when you need it.
Vaccines—typically, weakened strains of viruses or parts of bacteria—cause the body to produce antibodies for that specific infection. So rather than the usual delayed immune response that allows a cold virus to take hold, the antibodies produced by a measles vaccine are ready to knock out that disease before it ever gets started.
Vaccines are a kind of immune-insurance policy. Although the body
comes stocked with millions of different antibodies, there is
always the chance that the one you need won't be available when you
need it. Vaccines—typically, weakened strains...
More