Epidemics and pandemics have happened throughout the history of mankind. Before the end of the 20th century, scientific progress successfully eradicated several of the pathogens. While no one has to be afraid of smallpox anymore, there are some new pathogens that have never caused human disease before. Coronaviruses are a family of enveloped RNA viruses. In the 21st century, three of them have caused serious pandemics, including severe acute respiratory syndrome in 2002 and Middle East Respiratory Syndrome in 2012. In 2019 severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused the coronavirus disease-19 (COVID-19) pandemic, which has destroyed hundreds of thousands of lives and continues to rage.