Podcasts · Science for Kids / Science's Not Boring: The Kids Science Podcast

What is a vaccine?

4 Aug 2026 · 11 min · S1 E427

Have you ever wondered what happens inside your body when you get a scrape or catch a cold? Get ready to shrink down to microscopic size, because there is an epic battle happening inside you right now! Your body has a built-in security team with billions of invisible hunters, including giant white blood cells called macrophages that eat germs like hungry bears! But how does your body learn to fight off the really tough bad guys? We are traveling back in time to 1796 to meet Dr. Edward Jenner, a milkmaid named Sarah, and a very special cow named Blossom. Discover the incredible true story of how a mild sickness called cowpox helped defeat a terrifying disease called smallpox. You will find out how scientists discovered they could give your immune system a safe practice run by handing your cells a "wanted poster" of the germs, creating the world's very first vaccine! From giant germ-eating cells to memory cells that patrol your blood forever, join Mira and Finn for a fascinating journey into the microscopic superhero movie happening inside you every single day!