There’s nothing as relatable as a Star Wars analogy to explain something totally unrelated. Randall Munroe goes back to the original Star Wars movie (now called A New Hope) to show how the newfangled COVID-19 vaccines work, at xkcd.
The various parts of the analogy are broken down at Explain xkcd. You’ll learn even more in the discussion at Metafilter.
(ImageCredit: Randall Munroe/xkcd/CC BY-NC 2.5)