Discussion
Considering the 5 years from 2015 to 2019, the proportion of severe cases requiring intensive care and the case fatality ratios were strikingly similar among COVID-19 and German pneumonia patients. However, based on these data, COVID-19 may affect a younger cohort, which seems not fully explained by the different age structure of the Chinese population. As reported by the China Centre for Disease Control and Prevention, there seems to be a higher risk for severe disease in older ages and in patients with chronic illnesses [16]. But severity in younger adults below 60 years and in patients without chronic preconditions appears to be higher in COVID-19 patients than in pneumonia patients usually seen during the influenza season. The rate of ARDS and of patients requiring ventilation was markedly higher among COVID-19 patients with much longer duration of ventilation, based in the data from one study. During the influenza pandemic 2009 however, specialised German hospitals reported similarly long ventilation duration times [17].
The case series from outside Hubei report much milder symptoms than those reported from Hubei, especially from Wuhan, which may be due to early admittance of contact persons and of suspected cases with only mild symptoms. In addition, the large impact on the health system in the initially affected province resulted in insufficient healthcare resources [3]. This may have inhibited adequate treatment as the strikingly higher case fatality indicates [18]. However, all COVID-19 case series were still open with more than half of the cases hospitalised at reporting date. It is known that COVID-19 cases can have a prolonged course with many fatalities occurring 3 weeks after symptom onset [19]. Case fatality rates from these COVID-19 case series can therefore only be seen as preliminary.
Moreover, variations in health systems that could result in over- or underdiagnosis of chronic comorbidities such as COPD [20,21] are unaccounted for and may contribute to some of the observed differences between COVID-19 and SPP.