Read the text and fill in the gaps with the words from the table.
antibodies, chickenpox, immunity, infection,
lymphocytes, microorganism, vaccinations, vaccine
We can trick the body into responding to an __________ without actually becoming ill. Do you remember going to the doctor to get _____________ against ____________, hepatitis B and measles when you were younger? Vaccines are “pretend” infections. The vaccine is either made from a very small amount of the dead ___________ or the toxins that it makes. When you receive the vaccine the white blood cells (_________________) identify them and begin to make antibodies against the infection, but because the microorganism is dead (or not even there), you do not get ill. Just as with natural ___________, these antibodies stay in the bloodstream for a very long time. Therefore, when you are exposed to the live microorganism, ____________ are produced rapidly and you will not become ill. This is known as artificial immunity. Many infections can now be avoided by being given the ____________ for them before we come into contact with the live versions.