On May 16, 1918, the Spanish flu pandemic began to spread across the globe, infecting nearly one-third of the worlds population and killing an estimated 50 million people. The flu was particularly deadly to young, healthy adults, unlike most influenza viruses that primarily target the very young or elderly. The pandemic overwhelmed healthcare systems and caused widespread panic. The Spanish flu eventually faded, but it had a lasting impact on public health and global preparedness for future pandemics. The virus remains one of the deadliest in history.