Nowadays, newly evolved Coronaviruses have posed a global threat to public health[10, 11]. Although, the epidemiological and clinical characteristics of patients were well documented, understanding of the clinical spectrum of COVID-19 infection is still limited. As a human-to-human transmission disease, middle-aged and elderly patients with underlying comorbidities are susceptible to respiratory failure and may have a poorer prognosis[12, 13]. Explore the risk factors related to the prognosis would be helpful for doctors to take an even more effective treatment. In this study, we systematically investigated the effect of WBC on mortality. Our results showed that the death risk was associated with the WBC level at admission, although the index is at the normal range, those with higher WBC level patients were facing a much higher death possibility. These results were not reported elsewhere.
Although epidemiology and the genome had been well elucidated, much remain unknown. The risk factors which influence death are still not clear and until now. The immune system is essential to control and eliminate CoV infections. Nevertheless, accumulating evidence suggests that patients with severe COVID-19 might have a cytokine storm syndrome[14–16]. Patients of COVID-19 with maladjusted immune responses, may result in immunopathology and dead. Followed a deeper understanding of the interaction between Coronaviruses and the innate immune systems of the hosts may shed light on the development and persistence of inflammation in the lungs
Liu et al. had observed that nearly 80% of the patients had normal or decreased white blood cell counts, and 72.3% (99/137) had lymphocytopenia. Zhang et al. had also reported a result of 9 patients, which their peripheral white blood cell counts were most normal And PCT were all negative. These results were similar with ours. In our study we had found that most of the patients were with a normal range of WBC level. However, those with higher WBC lever patients were at a high risk of death.
Notable achievements have been made in understanding of COVID-19. As a largest known viral RNA genome, coronaviruses are enveloped, nonsegmented, positive-sense single-stranded RNA virus genomes in the size ranging from 26 to 32 kilobases. However, the relationship of the virus with immune system is still unknow. Gaining a deeper understanding of the interaction between Coronaviruses and the innate immune systems may shed light on the treatment of lung inflammation caused by CoVs. Our study had only observed a phenomenon, the potential mechanism still worth exploring. In addition, some limitations still exist, such as due to the limited number of patients and death cases, the conclusion needs to be verified by larger samples. Meantime, a dynamic WBC level during the treatment were not observed. Thus, the results should be considered as preliminary ones and further research is necessary.