In December 2019, an outbreak of severe acute respiratory infection COVID-19 (CoronaVirus Disease-19) caused by a novel coronavirus SARS-CoV-2 occurred in China. Since then, the virus has spread to nearly all countries and infected more than 1 million of people. World Health Organization has declared a pandemic because of the spread of the virus. The COVID-19 epidemic is a third one caused by coronaviruses, the first two being severe acute respiratory syndrome of 2002–2003 and Middle-East respiratory syndrome. In the present review, we briefly summarize information related to COVID-19. We review factors of innate and adaptive immune defense against epidemia-causing coronaviruses as well as mechanisms of viral evasion from the immune response. We also review potential mechanisms underlying the main feature of severe coronavirus infections, namely excudative pneumonia that, in a significant proportion of patients, develops into interstitial pneumonia and acute respiratory distress syndrome. Finally, we provide information concerning potential strategies of immunoprevention and immunotherapy of coronavirus infections.