1/3 of the world population was infected during which flu event?

• A. Flu Epidemic of 1917
• B. Asian Flu of 1957
• C. Hong Kong Flu of 1968
• D. Measles Outbreak of 1950s

Answer: (A)

The key idea is how broadly a flu outbreak spreads and how many people it infects worldwide. The 1918-1919 influenza pandemic, often called the Spanish flu, swept across the globe and infected roughly one-third of the world’s population. Its rapid spread and lack of immunity in the population led to an enormous, unprecedented reach in a single outbreak.

The other events were serious pandemics, but they did not reach that same global scale of infection. The Asian Flu of 1957 and the Hong Kong Flu of 1968 caused many illnesses and deaths, but a smaller share of people worldwide were infected. The measles outbreak is not a flu pandemic at all, and its impact is measured differently.