A large family of enveloped viruses that cause respiratory illness of varying severities, coronaviruses have become a household name due to the global COVID-19 pandemic. Only seven coronaviruses are known to cause disease in humans, four of which most frequently cause symptoms of the common cold. Three of the seven coronaviruses, however, have more serious outcomes in people. These include (1) SARS-CoV-2, a novel coronavirus identified as COVID-19; (2) MERS-CoV, identified in 2012 as the cause of Middle East respiratory syndrome (MERS); and (3) SARS-CoV, identified in 2002 as the cause of severe acute respiratory syndrome (SARS). The virus that causes COVID-19 continues to evolve and several variants of concern have been identified. Research is ongoing to better understand these variants, how easily they might be transmitted, and the effectiveness of currently approved vaccines against them.