coronavirus diseases coronavirus diseases coronavirus diseases are caused by viruses in the coronavirus subfamily, a group of related rna viruses that cause diseases in mammals and birds. in humans and birds, the group of viruses cause respiratory tract infections that can range from mild to lethal. mild illnesses in humans include some cases of the common cold (which is also caused by other viruses, predominantly rhinoviruses), while more lethal varieties can cause sars, mers and covid-19. as of 2021, 45 species are registered as coronaviruses, whilst 11 diseases have been identified, as listed below. for the disease involved in the ongoing pandemic since 2019, see covid-19. coronaviruses types alphacoronavirus betacoronavirus gammacoronavirus deltacoronavirus diseases common cold sars mers covid-19 vaccines covid-19 vaccine epidemics and pandemics sars (2002–2004) mers 2012 2015 2018 covid-19 (2019-present)