| 100% | SMALLPOX | 8 | Disease eradicated by the world's first vaccine |
| 54% | SMALLPOX | 8 | Viral disease cured by the first vaccine |
| 47% | POLIO | 5 | Disease largely eradicated by Salk's vaccine |
| 46% | COWPOX | 6 | Edward Jenner used it when developing the world's first successful vaccine |
| 44% | SPUTNIK | 7 | The world's first constructed satellite |
| 43% | HAITI | 5 | The world's first Black-led republic |
| 42% | RUSSIA | 6 | The world's largest country by area |
| 41% | SAFFRON | 7 | The world's most expensive spice by weight |
| 41% | NEPALIS | 7 | People represented by the world's only non-rectangular national flag |
| 41% | LONDON | 6 | Site of the world's first subway |
| 41% | NAPLES | 6 | Site of the world's first pizzeria |
| 40% | YELLOWSTONE | 11 | The world's first national park, located in Wyoming, Montana, and Idaho |
| 40% | HATH | 4 | Verb in the world's first telegraph message |
| 40% | SEIKO | 5 | Maker of the world's first quartz watch |
| 39% | NEWHAVEN | 8 | City with the world's first telephone directory (1878) |
| 39% | NIHAO | 5 | "Hello," in the world's most common first language |
| 39% | TELETHON | 8 | Milton Berle hosted the world's first one |
| 39% | SNUPPY | 6 | Afghan hound, the world's first cloned dog |
| 39% | LOST | 4 | "The ___ World," first book featuring the character of Professor Challenger created by Arthur Conan Doyle |
| 39% | WASTELAND | 9 | The —, modernist poem in five sections by T S Eliot first published in 1922 |
| 39% | RABIES | 6 | Disease for which Pasteur created the first vaccine |
| 39% | BOSTON | 6 | Site of the world's first city marathon in 1897 |
| 39% | MERCEDESBENZ | 12 | Maker of the world's first diesel-powered passenger car |
| 39% | WASHINGTONMACHINE | 17 | Appliance invented by the first U.S. president? |
| 39% | POLIO | 5 | Disease targeted by Salk's vaccine |
| 38% | BLIGHTY | 7 | Term for England used by soldiers of the First and Second World Wars |
| 38% | MANNHEIM | 8 | Where Karl Benz debuted the world's first auto |
| 38% | RCA | 3 | Co. that launched the world's first communications satellite |
| 38% | POLIO | 5 | Disease targeted by Jonas Salk's vaccine |
| 38% | DAKOTAFANNING | 13 | "War of the Worlds" star who goes by her middle name, not her first name, Hannah: 2 wds. |