SARS (Severe Acute Respiratory Syndrome) coronavirus caused a global outbreak in 2002–2003, resulting in over 8,000 cases and nearly 800 deaths across 37 countries. It is classified as an 'emergent' virus — one that has newly appeared in a population or rapidly expanded in host range, geographic distribution, or severity. MERS (Middle East Respiratory Syndrome) is also emergent but caused fewer deaths. SARS-CoV-2 (COVID-19) is the most recent example.