COVID-19, SARS and MERS: are they closely related?
BACKGROUND: The 2019 novel coronavirus (SARS-CoV-2) is a new human coronavirus which is spreading with epidemic features in China and other Asian countries with cases reported worldwide. This novel Coronavirus Disease (COVID-19) is associated with a respiratory illness that may cause severe pneumonia and acute respiratory distress syndrome (ARDS). Although related to the Severe Acute Respiratory Syndrome (SARS) and the Middle East Respiratory Syndrome (MERS), COVID-19 shows some peculiar pathogenetic, epidemiological and clinical features which have not been completely understood to date.
OBJECTIVES: We provide a review of the differences in terms of pathogenesis, epidemiology and clinical features between COVID-19, SARS and MERS.
SOURCES: The most recent literature in English language regarding COVID-19 has been reviewed and extracted data have been compared with the current scientific evidence about SARS and MERS epidemics.
CONTENT: COVID-19 seems not to be very different from SARS regarding its clinical features. However, it has a fatality rate of 2.3%, lower than SARS (9.5%) and much lower than MERS (34.4%). It cannot be excluded that because of the COVID-19 less severe clinical picture it can spread in the community more easily than MERS and SARS. The actual basic reproductive number (R0) of COVID-19 (2-2.5) is still controversial. It is probably slightly higher than the R0 of SARS (1.7-1.9) and higher than MERS (<1),. The gastrointestinal route of transmission of SARS-CoV-2, which has been also assumed for SARS-CoV and MERS-CoV, cannot be ruled out and needs to be further investigated.
IMPLICATIONS: There is still much more to know about COVID-19, especially as concerns mortality and capacity of spreading on a pandemic level. Nonetheless, all of the lessons we learned in the past from SARS and MERS epidemics are the best cultural weapons to face this new global threat.