Historical perspective: other human coronavirus infectious diseases, SARS and MERS

Alphacoronaviruses (HCoV-229E and HCoV-NL63) and betacoronaviruses (HCoV-OC43 and HCoV-HKU1) are common causes of upper respiratory tract infection in humans. SARS-CoV-1 and MERS-CoV emerged in 2002 and 2012, respectively, with the potential of causing severe and lethal disease in humans, termed SARS and MERS, respectively. Bats appear to be the common natural source of SARS-like coronaviruses including SARS-CoV-1, but their role in MERS-CoV is less clear. Civet cats and dromedary camels are the intermediary animal sources for SARS-CoV-1 and MERS-CoV, respectively. Nosocomial outbreaks are hallmarks of SARS and MERS. MERS patients with comorbidities or immunosuppression tend to progress more rapidly to respiratory failure and have a higher case fatality rate than SARS patients. SARS has disappeared since 2004, while there are still sporadic cases of MERS in the Middle East. Continued global surveillance is essential for SARS-like coronaviruses and MERS-CoV to monitor changing epidemiology due to viral variants.Copyright © ERS 2021.