How Do Vaccines Work? | Explained in Under 10 Minutes

In 1796, a country doctor in Gloucestershire took fluid from a cowpox blister on a milkmaid's hand and injected it into an eight-year-old boy. The experiment would be illegal today. It also led, two hundred years later, to the complete eradication of a disease that had killed three hundred million people in the twentieth century alone.Lewis leads the team through the science and the history: from tenth-century China, where dried smallpox scabs were blown into patients' nostrils, to Lady Mary Wortley Montagu bringing variolation to England in 1721, to the elegant biology of memory B cells — the immune system's way of remembering every pathogen it has ever defeated. The episode covers every major vaccine type, including a clear explanation of mRNA vaccines: how they work, why they were developed over thirty years before COVID, and why they do not — cannot — alter your DNA.The team don't avoid the harder parts of the story. The 1998 Wakefield fraud, the retracted Lancet paper, the measles resurgence that followed. The equity gap in COVID vaccine distribution, where rich countries sat at ninety percent coverage while low-income countries waited at twenty. Herd immunity, the economics of IP, and the political will — or lack of it — to distribute a life-saving technology fairly.Smallpox is gone from the Earth. Polio cases are down ninety-nine percent. Medicine has very few moments of complete victory — and this episode sits with one of them.Have a topic you'd love us to explain? Send your suggestions to [email protected] — we read every one!