2019 novel coronavirus (2019-nCoV) outbreak: A new challenge

3.1. Patients characteristics

Most of the patients were male (Table 1 ) with an age range of 8–92 years: interestingly, in the first period of this global epidemic there have been few cases in young people aged <15 years [1], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15]. Nevertheless, among known infected subjects outside of China, the prevalence of males and the age distribution at the time of diagnosis resemble those in the Chinese epidemic [4], [6], [15]. Although past medical histories were not always available [1], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], hypertension was the most reported underlying condition [1], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15] in as many as 80% and 31.2%, respectively, in the case series from Ren et al. [9] and Wang et al. [12]. Chen et al. [10] described mostly cardiovascular and cerebrovascular diseases (40%) in their population. Furthermore, Ren et al. [9] have reported underlying chronic liver disease in their whole population (n = 5) and this feature differs, at least so far, from the other cases of COVID-2019 [1], [4], [5], [6], [7], [8], [10], [11], [12], [13], [14], [15].

Huang et al. [1] and Wang et al. [12] have shown a rate of chronic obstructive pulmonary disease (COPD) of approximately 2% and 2.9%, respectively. Subsequently, Chen et al. [10] have reported a rate of approximately 1% for respiratory system diseases, different from an estimated COPD prevalence of between 1.2–8.9% in different regions of China [16]. Moreover, interstitial lung disease, history of smoking, bronchiectasis or asthma were underreported [1], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15]. Diabetes was first mentioned by Huang et al [1] and represented the main co-morbidity in their cohort (8/41; 20%), and thereafter other authors [11], [12] reported diabetes in approximately 10% of subjects. Furthermore, among cases outside Asia, Holshue et al. [4] have mentioned hypertriglyceridemia as the sole chronic illness of the first US case of COVID-2019; on the other hand, German cases [6] were overall healthy.

3.2. Signs and symptoms

Patients with confirmed 2019-nCoV infection mostly had respiratory signs and symptoms [1], [4], [5], [6], [7], [8], [9], [10], [11]. Fever was reported in all of the case series available, flanked by cough, mostly dry (Table 1). Dyspnoea was not uncommon and was reported in the entire cohort by Ren et al. (n = 5; 100%) [9]. A significant proportion of patients complained of gastrointestinal symptoms such as nausea, vomiting and diarrhoea, also appearing during the course of illness, a distinct feature [1], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15]: Holshue et al. [4] meticulously described the evolution of the first US case, complaining first of respiratory symptoms (i.e. dry cough) followed by abdominal discomfort and self-limiting nausea, vomiting and diarrhoea. There was myalgia or fatigue in 44–60% of Asian case series [1], [9].

3.3. Chest radiographic abnormalities

Multiple bilateral lobular and subsegmental areas of consolidation or bilateral ground-glass opacities were the main reported radiological features of COVID-2019 [1], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15]. In the 41 patients in the case series reported by Huang et al. [1], all had plain chest radiography (CXR) or computed tomography (CT) findings of pneumonia. Although CT is the best method to define the extension and typology of lung parenchyma involvement, CXR was mostly employed as a first investigation, probably because of the associated need to comply with infection control procedures [5].

3.4. Laboratory abnormalities

Leukopenia was the most common abnormality [1], [4], [5], [6], [7], [8], [9], reported in up to 63% of subjects in the study by Huang et al. [1]. Thrombocytopenia occurred in the reports by Holshue et al. [4] and Chen et al. [10] but is rarely reported in other series [1], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], although low platelets counts were found in up to 45% of severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV) infections [17], [18]. Nevertheless, abnormalities in hepatic [e.g. slight increase in aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels] and muscle (e.g. slight increase in creatine kinase or lactate dehydrogenase) enzymes were seen in early cases and later reported (Table 1) [1], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15]. As one might expect, C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) were frequently abnormal and, in contrast, most of the patients had normal procalcitonin (PCT) levels at admission: in the cohort of Huang et al. [1] up to 69% of patients had a PCT level of <0.1 ng/mL. Interestingly in the case series of Wang et al. [12] a prolonged prothrombin time was reported in approximately 58% of adults.

3.5. Complications and mortality

In one of the larger cohorts available by Huang et al. [1] with 41 patients, 4 (10%) had a superinfection and the risk increased with the intensity of care [intensive care unit (ICU) care 31% vs. no ICU care 0%; P = 0.0014], with almost all patients being treated with empirical antibiotic coverage during the acute phase. Furthermore, the risk of acute respiratory distress syndrome, with or without specific bacterial superinfection, complicated the clinical course of up to 29% of patients (12/41) [1]. In the same large cohort by Huang et al. [1], in up to 12% of cases an increase in troponin I count occurred, and five patients complained of an acute cardiac injury: this finding requires further study to assess the heart tropism of 2019-nCoV and the cardiovascular risk of infected patients during acute illness.

Chen et al. [10] reported a low rate (4%) of fungal isolates with a clinical need for empirical antifungal treatment, with one case of Candida glabrata, three cases of C. albicans and one case, more important, of Aspergillus flavus isolation. Moreover, the authors reported a lower rate of bacterial respiratory isolates, mostly Acinetobacter baumannii and Klebsiella pneumoniae [10]; according to that, microbiological data are poor to represent all of the 2019-nCoV-infected population, and the follow-up time reported in the literature is too short to define the real burden of post-viral infectious complications.

The first wave of 2019-CoV has caused 1775 deaths despite the severity of illness being mild in most of cases [1], [4], [5], [6], [7], [8], [9], [12], [14], [15]. Wang et al. [19] have interestingly reviewed the underlying diseases and demographic characteristics of deaths occurring in the Wuhan epidemic and found that older adults (>70 years) presented a shorter period between the first symptom and death compared with younger persons [11.5 (range 6–19) days vs. 20 (range 10–41) days; P = 0.033], as previously reported for other betacoronaviruses [17], [18]: this confirms the increased severity in the elderly for coronavirus illness [1], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15]. Furthermore, according to Wang et al. [19], 2019-CoV has developed a median period between the symptomatic phase to death (median 14 days) somewhat similar to MERS-CoV (median 14 days) and SARS-CoV (median 17.4 days) [12], [17], [18] (Table 2 ).