Asthma, Severe Acute Respiratory Syndrome Coronavirus-2 and Coronavirus Disease 2019

Dylan T. Timberlake; Kasey Strothman; Mitchell H. Grayson


Curr Opin Allergy Clin Immunol. 2021;21(2):182-187. 

In This Article


Coronaviruses are enveloped positive-sense RNA viruses under the order Nidovirales and family Coronaviridae.[3] There are currently 39 species in 27 subgenera of coronavirus with seven known to affect humans, called human coronaviruses (HCoVs). The seven HCoVs consist of severe acute respiratory syndrome coronavirus (SARS-CoV), Middle East respiratory syndrome coronavirus (MERS-CoV), SARS-CoV-2, and four non-SARS species.[4] The four non-SARS coronaviruses circulate in humans without animal reservoirs, which is in contrast to SARS-CoV, MERS-CoV, and SARS-CoV-2 that all originated from zoonotic spillover within the last two decades. The respective diseases for these viruses were reported in 2003 for SARS, 2012 for MERS, and 2019 for COVID-19.[4]

Non-SARS-HCoV infections are a common cause of upper respiratory tract[5] and severe lower respiratory tract infections in high-risk patients.[6] Although SARS-CoV and MERS-CoV are both HCoVs, the clinical presentation and disease of SARS and MERS varies significantly from that of non-SARS-HCoV. MERS and SARS may present as mild disease but can also present with more severe disease with acute respiratory distress syndrome (ARDS), having documented mortality rates of 5% in SARS and 29% in MERS.[7]