Zoonotic coronavirus epidemics: SARS, MERS, and COVID-19

Fung, Monica; Otani, Iris; Pham, Michele; Babik, Jennifer

OBJECTIVE: To review the virology, immunology, epidemiology, clinical manifestations, and treatment of the three major zoonotic coronavirus epidemics: severe acute respiratory syndrome (SARS), Middle East respiratory syndrome (MERS), and coronavirus disease 2019 (COVID-19). DATA SOURCES: Published literature obtained through PubMed database searches and reports from national and international public health agencies. STUDY SELECTIONS: Studies relevant to the basic science, epidemiology, clinical characteristics, and treatment of SARS, MERS, and COVID-19 with a focus on patients with asthma, allergy, and primary immunodeficiency. RESULTS: Whereas SARS and MERS each caused less than a thousand deaths, COVID-19 has caused a worldwide pandemic with nearly 1 million deaths. Diagnosing COVID-19 relies of nucleic acid amplification tests, and infection has broad clinical manifestations that can affect almost every organ system. Asthma and atopy do not appear to predispose patients to COVID-19 infection, but their effects on COVID-19 clinical outcomes remain mixed and inconclusive. It is recommended that effective therapies, including inhaled corticosteroids and biologic therapy, be continued to maintain disease control. There are no reports of COVID-19 among patients with primary innate and T-cell deficiencies. The presentation of COVID-19 among patients with primary antibody deficiencies is variable, with some experiencing mild clinical courses while others experiencing fatal. The landscape of treatment for COVID-19 is rapidly evolving, with both antivirals and immunomodulators currently with demonstrated efficacy. CONCLUSION: Further data is needed to better understand the role of asthma, allergy, and primary immunodeficiency on COVID-19 infection and outcomes.