spray – v. to put (something) on a surface or into the air using a special container that produces a stream of small drops of liquid or gas

vaccine – n. a substance containing killed or weakened organisms given to a person or animal to produce protection against a disease

infect – v. to make sick with something that causes disease

efficacy – n. the power to produce a desired result or effect

parasite – n. an animal or organism that lives in or on another animal or plant and gets food or protection from it

introduction – n. the act of bringing something into practice or use for the first time

Now it’s your turn to use these Words in This Story. In the comments section, write a sentence using one of these words and we will provide feedback on your use of vocabulary and grammar.