In December 2019, a cluster of patients with pneumonia of unknown cause was linked to a seafood wholesale market in Wuhan, China 1 At the time of this analysis, only a little over a month has passed since COVID-19 was first reported 1 . There are reasonable concerns about whether COVID-19 has undergone rapid or marked genomic mutation during transmission. Yet large cohort reports from outside Wuhan (Hubei Province) are not yet available, and the clinical characteristics of COVID-19 remain largely unclear. In this article, we describe the initial clinical, laboratory, and radiological characteristics of patients confirmed to have COVID-19 in Shanghai, and we compare the clinical features between patients with less severe illness and those requiring critical care. All rights reserved. No reuse allowed without permission. author/funder, who has granted medRxiv a license to display the preprint in perpetuity.
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The severity of COVID was defined based on the criteria established by China's National Health Commission 4 . 1. Mild. Minor symptoms only, without evidence for pneumonia by chest X-ray. 2, Moderate.
Fever and respiratory symptoms are present, and there is evidence for pneumonia by chest X-ray. 3. Severe.
Defined by any of the following conditions. 1) Dyspnoea, respiratory rate ≥ 30 /min, 2) resting hypoxia SaO2 ≤ 93%, 3) PaO2/FiO2 ≤ 300 mmHg. 4. Critical. The presence of any of the following conditions. 1) Respiratory failure, require mechanical ventilation, 2) shock, 3) other acute organ failure.
Median and interquartile range (IQR) or mean and standard deviation were calculated for continuous variables. Count and percentages were presented for categorical variables. Statistical Analysis was performed by using SPSS21.0. All rights reserved. No reuse allowed without permission. author/funder, who has granted medRxiv a license to display the preprint in perpetuity.
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Demographic and clinical characteristics. The demographic and clinical characteristics are shown in with diabetes, 12 (6.0%) with cardiovascular diseases, 4 (2.0%) with malignancy, and 6 (3.0%) with thyroid diseases.
The most common symptom identified was fever (86.9%). Patients' body temperatures were most commonly in a range from 38-38.9 °C (IQR). 10 (8.8%) patients presented with high fever greater than 39 .
Less than half of the patients presented with respiratory systems including cough (46.4%), sputum production (23.2%), itchy or sore throat (9.8%), shortness of breath (4.5%) and chest congestion (8.0%).
Myalgia or fatigue occurred in almost one-third (31.3%) of the patients. In addition, 5 (4.4%) patients had diarrhoea, which is suggestive of digestive system involvement (Table 1) .
No infections of health care workers were detected during the time interval studied. A history of recent travel to Wuhan, and contact with people from Wuhan was documented in 126 (63.6%) of the patients.
There was no difference in severity of disease between cases with Wuhan contact history and no-Wuhan contact history.
Of these 198 patients, 179 (90.4%) were admitted to isolation wards, including 3 mild and 176 moderate cases. 19 (9.5%) were admitted and transferred to the ICU because of the development of respiratory failure or other organ dysfunction, including 9 severe cases and 10 critical cases. 1 patient died All rights reserved. No reuse allowed without permission. author/funder, who has granted medRxiv a license to display the preprint in perpetuity.
The copyright holder for this preprint (which was not peer-reviewed) is the . https://doi.org/10.1101/2020.03.04.20030395 doi: medRxiv preprint without collecting sufficient data, and therefore was excluded from this study. Patient age differed significantly between the two groups (63.7 ± 16.8 for ICU vs 48.6 ± 15.6 for non-ICU patients). Male patients were significantly more common in ICU as compared with non-ICU cases (89.5% vs. 46.9%).
Moreover, patients with underlying cardiovascular diseases were significantly more common in ICU cases as compared with non-ICU cases (26.3% vs. 3.9%, P<0.01). Compared with the non-ICU, patients admitted to the ICU were more likely to have high fever with temperature over 38.5 o C (78.6% vs 37.6%), shortness of breath (36.8% vs 2.2%), and longer waiting period from onset of symptom to hospital admission (7 vs 4 days). 
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The copyright holder for this preprint (which was not peer-reviewed) is the . https://doi.org/10.1101/2020.03.04.20030395 doi: medRxiv preprint time (PT) (median 13.3, 12.9-13.8) and activated partial thromboplastin time (APTT, median 39.5, 36. 7-42.8) were normal in most patients. However, a marked rise in fibrinogen and CRP was observed in 108 (55.4%) and 152 (78.4%) cases, respectively. The majority of patients (65.4%) had decreased blood calcium concentration, while 19.5% cases had decreased blood sodium concentration.
Compared with the non-ICU patients, patients admitted to the ICU were more likely to have increased neutrophil count (15.8% vs 5.2%), decreased lymphocyte count (84.2% vs 0.6%), increased prothrombin time (26.3% vs 7.4%), increased APTT (42.1% vs 15.3), increased fibrinogen (78.9% vs 52.8%) and
increased D-dimer (63.2% vs 29.5%), as well as decreased levels of blood sodium (42.1% vs 17.0%) and calcium (100% vs 61.4%). By contrast, patients admitted to the ICU were less likely to have increased C-reactive protein (57.9% vs 80.6%). Table 2 : Admission blood cell count and coagulation function of patients with COVID-19 
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The copyright holder for this preprint (which was not peer-reviewed) is the 
All rights reserved. No reuse allowed without permission.
author/funder, who has granted medRxiv a license to display the preprint in perpetuity. author/funder, who has granted medRxiv a license to display the preprint in perpetuity. author/funder, who has granted medRxiv a license to display the preprint in perpetuity. All rights reserved. No reuse allowed without permission.
author/funder, who has granted medRxiv a license to display the preprint in perpetuity. All rights reserved. No reuse allowed without permission.
author/funder, who has granted medRxiv a license to display the preprint in perpetuity. 
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author/funder, who has granted medRxiv a license to display the preprint in perpetuity.
The copyright holder for this preprint (which was not peer-reviewed) is the Radiological findings. Of 198 patients who underwent chest computed tomography on admission, 98.5 % cases manifested abnormalities suggestive of pneumonia. The most common patterns on chest computed tomography were ground-glass opacity and bilateral patchy consolidation. Figure 1 illustrates representative findings with different degrees of radiological abnormalities from seven patients.
To determine the major clinical features that appeared during COVID-19 progression, the dynamic changes in 11 clinical laboratory parameters, including haematological and biochemical parameters, were tracked from day 1 to day 15 after the onset of the disease at 2-day intervals (Fig. 2 &3) . ICU patients were subdivided into two subgroups as described in the Methods section: severe and critical. The levels of CRP and procalcitonin in critically ill patients showed a trend for sustained elevation 9 days after admission (Fig. 2A&B) . White blood cells and neutrophils counts were higher in critical patients than in severe patients (Fig. 2C&D ). Most significantly, critical cases had more severe lymphopenia than severe cases (Fig 2E, < 0 .6 x 10 9 /L, P<0.05).
Critical cases had significantly more organ dysfunction and coagulation abnormalities than severe cases. Cardiac troponin I and myoglobin was higher in critical patients than in severe cases (Fig. 3A&B) ,
indicating heart injury. The levels of blood urea nitrogen (BUN) and creatinine level were higher in critical cases than in severe cases (Fig. 3C&D) , suggesting kidney injury. The level of D-dimer was higher in All rights reserved. No reuse allowed without permission.
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The copyright holder for this preprint (which was not peer-reviewed) is the . https://doi.org/10.1101/2020.03.04.20030395 doi: medRxiv preprint critically ill than in severely ill (Fig. 3E) , however, there was no marked difference in fibrinogen level between these two groups (Fig. 3F ).
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In this single centre cohort of confirmed COVID-19 cases in Shanghai, the median duration of symptoms from disease onset to hospital admission was 4 days. Compared to the previously reported duration of 7-10 days between symptom onset and hospitalization in Wuhan 3 5 6 , patients in Shanghai received earlier in-ward observation and medical service, most likely due to improved monitoring and increased awareness of the outbreak. As a result, our data likely were recorded closer to the onset date of the disease, which may explain some of the differences between the results reported from Wuhan and Shanghai.
In terms of patient's characteristics, we observed a comparatively equal male to female ratio in this study, which differs from the data reported in Wuhan 3 5 6 . This may be because most of these initial cases in Shanghai had a history of exposure in Wuhan (63.6%), and the disease thereafter appeared in a family cluster pattern. Almost half of the patients in Shanghai were under 50 years old, in contrast with the predominantly older patient population reported in Wuhan. In addition, 69 (34.8%) patients in our cohort had pre-existing comorbidities. Whether the disease is more likely to manifest in patients with comorbidities and/or older patients remains unclear and requires further study.
Regarding laboratory evaluation, low or normal levels of white blood cell (WBC) and neutrophil counts were present in COVID-19 patients upon admission. ESR and CRP levels were elevated in most patients. Although procalcitonin level was increased in over one-third (28.4%) of the patients, the median 0.03 (0.02-0.06) was close to normal range. These results are similar with that of two Wuhan cohort studies already published 3 5 . We further observed that serum lactate levels were above the normal upper range in the majority of patients (83.7%), indicating the likely presence of metabolic acidosis. The sensitivity of LACT in COVID-19 infection is similar to ESR and CRP. All rights reserved. No reuse allowed without permission.
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The copyright holder for this preprint (which was not peer-reviewed) is the . https://doi.org /10.1101 /10. /2020 In addition, we observed a marked reduction in T and T H subtype cells in infected patients, suggesting that SARS-Cov-2 infection may impair cellular immunity. It is known that MERS-CoV is able to infect both CD4 + and CD8 + primary human T cells and, upon infection induces T cell apoptosis in vitro 7 . While the cell surface receptor for SARS-Cov-2 has now been identified as ACE2 8 , other receptors may also exist on immune cells to bind to coronavirus [9] [10] [11] . As there is no proven antiviral treatment yet available, strategies to enhance the immune system may be considered. Since the most common haematological changes in COVID-19 patients were lymphopenia and immunodeficiency, we postulate that hematopoietic growth factors such as G-CSF, by mobilizing endogenous blood stem cells and endogenous cytokines, may represent a potential haematological treatment for COVID-19 patients 12 .
Interestingly, a noticeable increase of glutathione reductase (GR) level occurred in 40.2% of the COVID-19 patients in our cohort, while ALT and AST are normal in most patients. GR is an essential enzyme that recycles oxidized glutathione back to the reduced form 13 . GR is known to participate in an oxidative defence system required for effective immune responses against bacteria 14 15 . Whether GR is involved in host defence systems against viruses such as SARS-Cov-2 remains to be determined.
We observed that 65.4% of COVID-19 patients had decreased serum calcium levels. Calcium influx regulates both clathrin-mediated and clathrin-independent endocytosis during viral infection, thus constituting a key mechanism for regulation of influenza A virus internalization and infection 16 . Based on this theory, calcium channel blockers, including amlodipine, verapamil, and diltiazem, as well as BAPTA-AM, have been proven effective in inhibiting IAV replication in a dose-dependent manner in a canine kidney cell model 17 . Moreover, diltiazem may have both prophylactic and therapeutic effects in IAV treatment according to both ex vivo and in vivo testing 17 . We therefore propose the hypothesis that Ca 2+ levels and/or Ca 2+ channels may play a role in endocytosis and infection of SARS-Cov-2. Further studies are needed to characterize the functional importance of this potential pathway.
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The patients admitted to the ICU were more likely to be older, male, with temperature over 38.5 o C, symptom of dyspnoea, underlying cardiovascular disease, and longer waiting period from onset of symptom to hospital admission, compared to those not admitted to the ICU. This suggests that age, sex, high fever, admission time and co-morbidity are risk factors for disease severity. Compared with non-ICU patients, patients who received ICU care had numerous laboratory abnormalities. These abnormalities suggest that SARS-Cov-2 infection can be associated with cellular immune deficiency, coagulation activation, myocardial injury, hepatic injury and kidney injury. These laboratory abnormalities are similar to those previously observed in patients with MERS-Cov and SARS-Cov infection 18 19 .
The longitudinal profile of laboratory findings was dynamically tracked for those patients requiring ICU care. When these patients were subdivided into severe and critical ill subgroups, we observed that white blood cell count, neutrophil count, D-dimer, BUN, creatinine, myoglobulin and troponin I levels were higher in critical cases than in severe cases. Neutrophilia may be associated with secondary infection, while coagulation activation could be related to sustained inflammatory responses. Acute heart and kidney injury could be related to direct effects of the virus or possibly hypoxia 9 20 .
Our study has several limitations. First, although we obtained data from the initial 198 patients with laboratory-confirmed COVID-19 in Shanghai, the cohort is still relatively small. More patients need to be analysed to provide a comprehensive and precise description of the spectrum of disease associated with this infection. Secondly, our study reports primarily baseline results from patients upon hospital admission, and more longitudinal data regarding disease progression and clinical outcomes will require further collection and study. Despite these limitations, our study provides data from the first large cohort outside Wuhan and adds important laboratory information to the rapidly accumulating body of information about COVID-19.
These results will assist in multi-centre monitoring of the disease. All rights reserved. No reuse allowed without permission. author/funder, who has granted medRxiv a license to display the preprint in perpetuity.
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In conclusion, COVID-19 affects a wide-range of patients, from youth to the elderly. Fever is consistently the most common symptom of onset, but multiple other clinical manifestations occur, including a spectrum form T cell deficiency to symptoms of digestive system involvement. Older age, male, fever over 38.5 o C, symptom of dyspnoea, the presence of underlying cardiovascular disease, and longer waiting period from onset of symptom to hospital admission are risk factors associated with the severity of disease.
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The copyright holder for this preprint (which was not peer-reviewed) is the . https://doi.org/10.1101/2020.03.04.20030395 doi: medRxiv preprint Fig. 1 All rights reserved. No reuse allowed without permission. author/funder, who has granted medRxiv a license to display the preprint in perpetuity.
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