COVID-19 is a new infectious disease. Since the COVID-19 outbreak, the number of confirmed cases of the virus reached 82052 on the Chinese mainland as of the mid-April, and 3339 cases died [1] . Among them, the cumulative confirmed cases in Hubei Province and Wuhan accounted for 74.3% and 43.2% of the total cases in China, respectively, which is the top priority of epidemic prevention and control [2] . Wang et al [3] reported 138 novel coronavirus pneumonia hospitalized patients' clinical characteristics in Wuhan, China. Patients' common symptoms included of fever, fatigue and dry cough. Lymphopenia, prolonged prothrombin time and elevated lactated hydrogenase were occurred in most of hospitalized patients with COVID-19. With the COVID-19 spread rapidly throughout China, Guan et al [4] extracted data from 1099 patients in 30 provinces of mainland China reported that novel coronavirus pneumonia patients often presented without fever, and many did not have abnormal radiologic findings. The understanding of novel coronavirus pneumonia is a gradual exploration process. As so for, prevention and control protocol for Novel Coronavirus Pneumonia issued by General Office of National Health Commission have been updated to the version 7.
There is still no specific medicine for novel coronavirus pneumonia. COVID-19 is categorized as beta genus coronavirus, same as the two other strains-human severe acute respiratory syndrome coronavirus (SARS-Cov) and Middle East respiratory syndrome coronavirus (MERS-Cov) [3] . Antiviral agents recommended in prevention and control protocol for Novel Coronavirus Pneumonia (version 7) was mainly summarized by the antiviral therapy of MERS-Cov and SARS-Cov [6] . Lopinavir-ritonavir is an HIV protease inhibitors and its registered therapeutics is for the treatment of HIV infection. Lopinavir is screened from FDA-approved compound library that can inhibit MERS-CoV replication in the low-micromolar range. Moreover, lopinavir can also inhibit the replication of SARS coronavirus and human coronavirus 229E [7] . Arbidol is a RNA synthesis inhibitor which is used for the prophylaxis and treatment of Influenza A and B, SARS, Hepatitis B and C, Herpies, Dengue Fever, and RSV. Abidol have been identified effective with anti-coronavirus activity in vitro [8] . Therefore, the efficacy and safety of antiviral drugs in COVID-19 need to be further confirmed by the clinical trials. Meanwhile, there is little information of clinical antiviral therapy on the lopinavir-ritonavir alone or combined with arbidol in the COVID-19 patients. In the present study, we retrospective studied medical records of 73 hospitalized patients with COVID-19 and evaluated the antivirus efficacy of lopinavir/ritonavir alone or combined with arbidol.
The protocol was approved by the Ethics Committee of Lishui Hospital of Zhejiang University (Ethical Review of Clinical Research-2020-5) and was registered in Chinese Clinical Trail Registry (ChiCTR2000030391). Cases material of discharged patients were collected from February 21 to March 18, 2020 at Lishui Central Hospital, Zhejiang, China and Wuhan fourth hospital, Hubei, China, which is a designated hospital for COVID-19. All patients were diagnosed and treated according to the diagnosis and treatment protocol for novel coronavirus pneumonia issued by General Office of National Health Commission [5] . Inclusion criteria: (1) hospitalized patients with laboratory-confirmed COVID-19; (2) hospitalized patients with COVID-19 were treated with lopinavir-ritonavir alone or combined with arbidol for antiviral therapy. Exclusion criteria: (1) hospitalized patients with pneumonia caused by other pathogens; (2) hospitalized patients with COVID-19 haven't received lopinavir-ritonavir for antiviral therapy.
A total of 73 cases were eligible to participate which meet the inclusion criteria and exclusion criteria. 34 of the 73 patients who had been treated with lopinavir-ritonavir (400 mg and 100mg, orally) twice daily were identified to the Group-LR, and the remainder who had been treated with lopinavir-ritonavir (400 mg and 100mg, orally) twice daily combined with arbidol (200 mg, orally) three times a day was identified to the Group-LR+Ar. All eligible patients received supportive treatment if necessary, such as supplemental oxygen, noninvasive and invasive ventilation, antibiotic agents and vasopressor support.
Epidemiological, demographic, clinical, laboratory, radiological characteristics, treatment, and outcome data were collected through a review of electronic medical records. The data were reviewed by a trained team of physicians. Information recorded included demographic data, clinical presentation, medical history, laboratory values (ie, hematological parameters, biochemical parameters), time of virus negative, chest computed tomographic (CT) scans, and treatment measures during the hospital stay (ie, antiviral therapy, corticosteroid therapy, immunosuppressive therapy). The clinical classification of COVID-19 patients were carried out according to the diagnosis and treatment protocol for novel coronavirus pneumonia issued by General Office of National Health Commission [5] . The laboratory test results were grouped by admission time on the day 0-2, 3-5, 6-9, 10-14, and >15.
The primary end point was the rate of cure, defined as hospitalized patients with COVID-19 meet the discharge criteria. The discharge criteria were as follows [5] : 1) Body temperature is back to normal for more than three days; 2) Respiratory symptoms improve obviously; 3) Pulmonary imaging shows obvious absorption of inflammation; 4) Nuclei acid tests negative twice consecutively on respiratory tract samples such as sputum and nasopharyngeal swabs (sampling interval being at least 24 hours). Secondary end points were hospital stay, the rate of COVID-19 RNA clearance, the time of nucleic acid turning negative and symptoms disappeared to admission. The result and time SARS-COV-2 nucleic acid test of respiratory samples was subject to the last test. If the COVID-19 nucleic acid was negative for two consecutive tests, the first test time was used for nucleic acid turning negative.
Categorical variables were described as frequency rates and percentages, and continuous variables were described using mean, median, and inter quartile range (IQR) values. Proportions for categorical variables were compared using the χ2 test, although the Fisher exact test was used when the data were limited. Continuous variables were expressed as means ± SD when the data were normally distributed, and means were compared using in dependent group t tests; otherwise, data (nonnormal distribution) were expressed as median and inter quartile range using the Mann-Whitney test. All statistical analyses were performed using SPSS (Statistical Package for Results the Social Sciences) version 16.0 software (SPSS Inc). P < 0.05 was considered to be significantly different between the two groups.
Of these 73 hospitalized patients with COVID-19 who was discharged from February 8 to March 13, 2020. The largest number of patients (60) had been admitted to Wuhan fourth hospital. The rest of patients were from Lishui Central Hospital. The demographic and clinical characteristics of the patients were shown in Table 1 . The mean age of group-LR+Ar was 52.3±15.8 years (range, 21-81 years), and 26 (66.7%) were men. The mean age of group-LR was 59.5±13.6 years (range, 30-87 years), and 11 (32.4%) were men. The differences of mean age and sex ratio between group-LR+Ar and group-LR patients had statistically significant. Number of patients in all level of ages has no statistical difference. In the group-LR+Ar, the ratio of ordinary and heavy type of COVID-19 was 71.8% and 29.2%, respectively. The ratio of ordinary and heavy type of COVID-19 was 61.8% and 38.2% in the group-LR. Some patients had one or more coexisting medical conditions. Hypertension, coronary heart disease and diabetes were the most common comorbidities. 15 (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.
The copyright holder for this preprint this version posted April 29, 2020. 
The antiviral efficacy of lopinavir-ritonavir alone or combined with arbidol in the treatment of 73 hospitalized patients with COVID-19 were shown in Table 2 . In the group-LR+Ar, 36(92.3%) patients were cured and discharged from hospital, and 2(5.1%) patients were admitted and transferred to the ICU because of the condition aggravation. In the group-LR, 33(97.1%) were cured and discharged from hospital with no patients were transferred to the ICU. The mortality was 2.6% and 2.9% in group-LR+Ar and group-LR, respectively. The rate of COVID-19 RNA clearance was 92.3% of group-LR+Ar and 97.1% of group-LR. Removed 3 patients who transferred to ICU or died in the group-LR+Ar, the time of nucleic acid turning negative was 11.5±9.0 days and hospital stay was 14.4±7.9 days. Removed 1 died case in the group-LR, the time of nucleic acid turning negative was 9.9±7.5 days and hospital stay was 16.0±9.0 days. Of the 39 patients in the group-LR+Ar, the pulmonary image manifestations of 33(84.6%) patients were absorbed at discharged, included of less absorption and marked improvement. 13(38.2%) patients were absorbed at discharged in the group-LR. No absorption of pulmonary image manifestations had 2 cases in each group. 4(10.3%) patients' chest CT findings were worsened in group-LR+Ar and 1 case was worsened in group-LR. Fever, cough and chest tightnessd were the main symptoms in hospitalized patients with COVID-19. The disappearance time of fever, cough and chest tightnessd in the group-LR+Ar were 3.4±2.7, 9.0±6.2 and 6.0±2.1 days while they were 2.6±3.4, 6.6±5.0 and 10.1±3.0 days in the group-LR, respectively. Table 2 . Comparison of the primary end point and secondary end points between group-LR+Ar and group-LR Variable LR+Ar (N=39) LR (N=34) P value All rights reserved. No reuse allowed without permission.
(which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.
The copyright holder for this preprint this version posted April 29, 2020. 
6 clinical laboratory parameters included of white blood cell, neutrophil, lymphocyte, monocyte, C-reactive protein and procalcitonin were tracked during their hospitalization. Dynamic changes of the laboratory parameters was classified on the day 1-2, 3-5, 6-9, 10-14 and after 15 since the patients admitted to hospital (Figure 1 ). There were no significant differences in 6 clinical laboratory parameters between group-LR+Ar and group-LR. Mean white blood cell and neutrophil count were in normal range in both two groups. The level of lymphocyte count decreased in both two groups that next to the lower normal limit, the minimum was at 3-5 days after admitted to hospital. Both of the two groups were in low level of lymphocyte at 0-15 days after hospitalization with no significant difference. On the contrary, the level of monocyte was next to the upper normal limit. The level of the inflammatory biomarker C-reactive protein was marked increased in early hospitalization of both (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.
The copyright holder for this preprint this version posted April 29, 2020. . two groups, and then gradually declined over time during hospitalization. Mean C-reactive protein of was higher in group-LR than that in group-LR+Ar. Mean value of procalcitonin was slightly higher than the upper normal limit with no significant difference between two groups. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.
The copyright holder for this preprint this version posted April 29, 2020. . lymphocytes, and then damage the immune system during disease [16] . CRP is a useful gauge of inflammation. From the trend of CRP，CRP values of hospitalized patients with COVID-19 were increased slightly at admission and then decreased gradually. It is suggested that host defense against invading pathogens as well as inflammatory response. PCT is sensitive indicator of bacterial infection [17] . The profile of PCT levels was relatively stable with no markedly raise.
Our trial has several limitations. First, this study was a retrospective analysis with no randomized, future prospective study can overcome this defect. Second, there were only 73 COVID-19 cases in this study. According to the study data of lopinavir-ritonavir in the treatment of severe COVID-19 cases [11] , we concluded that the sample size need 300 subjects to evaluate the efficacy of lopinavir-ritonavir combined with abidor was better or worse than that of the single drug treatment of lopinavir-ritonavir. Third, the age and gender of two groups were not balanced because of the small sample. However, there was no significant difference between groups after stratification of gender and age. In the future, increasing the number of research samples can improve the test efficiency and enhance the credibility of research results. Finally, the results of this study suggested that the overall treatment effect of COVID-19 was well. It was difficult to judge the antiviral effect using cure rate and virus turning negative rate as the primary endpoints. Therefore, it may be more feasible in clinical practice to find a more suitable COVID-19 population or primary endpoints for evaluating the therapeutic effect of antiviral drugs, such as evaluating whether it can reduce mortality in severely ill population.
In conclusion, we found that lopinavir-ritonavir alone or combined with arbidol treatment did not significantly increase cure rate, reduce hospitalization time, raise virus negative rate, and diminish virus negative time in hospitalized patients with COVID-19. These preliminary results could inform future trials of COVID-19 to evaluate this and other medication in the treatment of infection with SARS-CoV-2. Whether lopinavir-ritonavir combined with other antiviral drugs might enhance antiviral effects and improve clinical outcomes need more clinical observations.
The data used to support the findings of this study are available from the corresponding author upon request.
The authors declare that they have no conflicts of interest.