Coronavirus is a group of viruses that infect respiratory tract. This group was identified in 1960s. Uptil now, there are seven common types of coronavirus. 1. 229E (alpha coronavirus) 2. NL63 (alpha coronavirus) 3. OC43 (beta coronavirus) 4. HKU1 (beta coronavirus) 5. MERS-CoV (the beta coronavirus that causes Middle East Respiratory Syndrome, or MERS) 6. SARS-CoV (the beta coronavirus that causes severe acute respiratory syndrome, or SARS) 7. SARS-CoV-2 (causes COVID-19)