Swine flu, officially known as H1N1 influenza, is a contagious respiratory illness caused by influenza viruses that typically infect pigs but can also spread to humans. Understanding how swine flu spreads, 어떻게 진단되는가, and how to prevent it is essential for protecting public health—especially during seasonal outbreaks. What Is Swine Flu? Swine flu is an influenza A virus …