Chinese and Italian COVID-19 outbreaks can be correctly described by a modified SIRD model

Diego Caccavo

The COVID-19 disease, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has spread rapidly in the first months of the 2020 and the World Health Organization (WHO) on the 11 th of March declared a global pandemic [1] . COVID-19 symptoms are often (80%) mild [2] , may appear 2-14 days after exposure (mean incubation period 5-6 days) [2] , and include fever, cough and shortness of breath [3] . However the 13.8% of infected have severe disease and the 6.1% are critical (respiratory failure, septic shock, and/or multiple organ dysfunction/failure) [2] . Mild cases typically recover within two weeks, while those with severe or critical disease may take three to six weeks to recover. Among those who have died, the time from symptom onset to death has ranged from two to eight weeks [2] . In the severe and critical disease, the patient admission to intensive care unit (ICU) is necessary and the mechanical ventilation (artificial assistance to support breathing), may be required [4] . This special treatment is the bottle neck of most of the health care systems, which are not prepared to deal with the numbers of patients that the COVID-19 disease could produce. Therefore, measures of containment of the SARS-CoV-2 outbreaks are essential to not overstress the health care systems and to manage the pandemic.