Chloroquine, arbidol (umifenovir) or lopinavir/ritonavir as the antiviral monotherapy for COVID-19 patients: a retrospective cohort study

Background: The severe acute respiratory syndrome coronavirus-2 outbreak was identi�ed in China in December 2019 and spread worldwide, reaching the pandemic levels. However, a speci�c, effective and proven therapy for the patients with coronavirus disease 2019 (COVID-19) remains elusive. We aim to compare the e�cacy and the safety of three antiviral monotherapies (chloroquine phosphate, arbidol (Umifenovir) or lopinavir/ritonavir) in non-severe, hospitalised COVID-19 patients. Methods: We retrospectively analysed the hospitalised, laboratory-conrmed COVID-19 patients, treated with antiviral monotherapies at Huizhou Municipal Central Hospital between Jan 19 and Mar 16, 2020. Demographic and clinical data were extracted from electronic medical records. The primary outcome of the study was the viral shedding interval. Results: Twenty-seven patients with COVID-19 were included in the study with 10 receiving chloroquine phosphate, 11 receiving arbidol and 6 receiving lopinavir/ritonavir. Baseline demographics and clinical data were similar between groups. The median viral shedding interval in the lopinavir/ritonavir group was 13.0 days (95% CI: 12.2-23.8), while signi�cantly shorter in the chloroquine group at 5.0 days (95% CI: 0.4-9.6) (p=0.003). A reduced median interval was also observed in the arbidol group, with 8.0 days (95%CI: 4.9-11.1) (p=0.008). Moreover, the hospitalisation duration was shorter in the chloroquine (9.3 ± 1.8 days, p<0.001) and arbidol groups (11.7 ± 3.7 days, p<0.001), and the hospitalisation costs were signi�cantly reduced in the chloroquine (USD 1327 ± 566, p=0.001) and arbidol groups (USD 1167 ± 434, p<0.001), when compared with the lopinavir/ritonavir group (hospitalisation length and costs: 19.7 ±


Background
The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) outbreak was identi ed in China in December 2019 [1].As of April 5, 2020, a total of 1,133,758 laboratory-con rmed cases of coronavirus disease 2019 (COVID-19) were reported globally, including 62,784 deaths [2].The SARS-CoV-2 has spread rapidly, reaching the pandemic levels and demanding sustained global attention.However, currently, treatments remain supportive, and clinicians continue to lack a safe and effective antiviral regimen, which is speci c to the SARS-CoV-2 and capable of reducing viral load, thus limiting the transmission potential and improving the prognosis.Therefore, identifying a clinically effective drug is considered urgent and essential in the ght against COVID-19.
According to the genome sequences and protein structure analysis, the SARS-CoV-2 is remarkably similar to the SARS-CoV implicated in the 2003 outbreak [3,4].Hence, it is reasonable to focus our attention on reviewing existing antiviral drugs which were previously used for SARS-CoV, so as to potentially identify effective drugs for use against the current SARS-CoV-2 [5].Previous studies reported that chloroquine, arbidol (Umifenovir) or lopinavir/ritonavir could inhibit the activity of the SARS-CoV in-vitro, but their clinical e cacy in-vivo remains unknown [6][7][8].In this study, we aim to compare the e cacy and the safety of these three antiviral monotherapies (chloroquine phosphate, arbidol (Umifenovir) or lopinavir/ritonavir) in non-severe, hospitalised COVID-19 patients.

Study design and participants
This is a retrospective cohort study that included hospitalised, laboratory-con rmed COVID-19 patients at Huizhou Municipal Central Hospital between Jan 19 and Mar 16, 2020.The included patients had been treated with different antiviral monotherapies (chloroquine phosphate, arbidol (Umifenovir) or lopinavir/ritonavir) and were identi ed from electronic medical records.All patients have already been discharged from hospital.The ethics committee of the Huizhou Municipal Central Hospital approved this study, and the trial was registered with www.chictr.org.cn(ChiCTR2000030931).The antiviral monotherapy regimens of the patients included one of the following: 500mg chloroquine phosphate 12-hourly, 200mg arbidol (Umifenovir) 8-hourly or 400mg/100mg lopinavir/ritonavir 12-hourly, not exceeding 10 days of use.Therapy was commenced immediately after the diagnosis with COVID-19 was made.The patients' supportive treatments were in accordance with the Chinese COVID-2019 diagnosis and treatment guidelines [9].
The guideline identi es 4 categories of COVID-19 patients, according to severity [9].Mild patients demonstrate mild respiratory symptoms without lung in ltration, while common patients demonstrate lung in ltration together with fever or respiratory symptoms.Severe patients demonstrate dyspnoea (respiratory rate ≥ 30/min), hypoxia (oxygen saturation ≤ 93%, partial pressure of oxygen/ fraction of inspired oxygen ≤ 300mmHg), or signi cant progression of chest imaging lesions >50% within 24-48 hours, while critical-severe patients demonstrate respiratory failure requiring mechanical ventilation, shock, or organ failure, requiring ICU admission [9].

Data collection
Two clinicians (Y.F.X and J.J.Y) independently collected demographic and clinical data from electronic medical records using standardised data collection forms, with any variances or discrepancies being discussed, and the validity of disputed data being moderated and adjudicated by a third clinician (C.Q.L).

Outcomes
The primary outcome of the study was the viral shedding interval, determined by the RT-PCR of the respiratory specimen.Secondary outcomes included the length of hospital stay, hospitalisation expenses, the percentage of patients who still tested positive for SARS-CoV-2 at day 10 and day 14 and the adverse events associated with each therapy.The hospitalisation expenses in this study were expressed in United States Dollars (USD) with an exchange rate of USD1 = Chinese Yuan 7 on April 3, 2020.

Statistical analysis
Data analysis was conducted using SPSS Version 19.0 (IBM SPSS Statistics, Armonk, NY, USA).Data were presented as mean±standard deviation, median (interquartile range [IQR]) or n (%), where appropriate.Continuous variables were compared using one-way analysis of variance for the normally distributed data, with a non-parametric test for data that was not normally distributed.For categorical variables, Pearson's chi-squared test or Fisher's exact test was used.Bonferroni correction was used for the post-hoc multiple comparisons.The viral shedding interval was evaluated using the Kaplan-Meier method and differences were assessed with the log-rank test.Two-tailed p-values <0.05 were considered statistically signi cant.
After 10 days of treatment, the SARS-CoV-2 testing by RT-PCR was negative for 9 patients (90%) in the chloroquine group (p=0.001) and 8 patients (72.7%) in arbidol group (p=0.009),while comparatively the lopinavir/ritonavir group had no patients testing negative (0/6).Additionally, after 14 days, all the patients in the chloroquine (p=0.036>0.05/3)and arbidol groups (p=0.029>0.05/3)tested negative, while only 3 patients (50%) had tested negative in the lopinavir/ritonavir group.No statistically signi cant difference in outcome was noted on day 10 or day 14 between the chloroquine and arbidol group.
Adverse events during the treatment period included: 2 patients (20%) in the chloroquine group reported nausea, vomiting, dysphoria or blurred vision, compared with 1 patient (9.1%) in the arbidol group and 3 patients (50%) in the lopinavir/ritonavir group reported diarrhoea.No statistically signi cant difference was noted between groups.(p=0.133).Although 1 patient in the chloroquine group required drug withdrawal on day 6 due to dysphoria and blurred vision, all the other cases of adverse effects were relieved with supportive treatment.

Discussion
This is the rst study to retrospectively compare the clinical safety and e cacy of antiviral monotherapies (chloroquine, arbidol (Umifenovir) or lopinavir/ritonavir) in non-severe, hospitalised COVID-19 patients.We found that patients treated with lopinavir/ritonavir demonstrated longer viral shedding intervals and hospitalisation durations, as well as increased hospitalisation costs and adverse effects.Additionally, chloroquine and arbidol demonstrated decreased viral shedding intervals and hospitalisation durations, together with reduced hospitalisation costs.The chloroquine group demonstrated a reduced median viral shedding interval and hospitalisation duration, while the arbidol group showed a lower cost of hospitalisation and rate of adverse effects.
Despite the SARS-CoV-2 outbreak currently being under control in China, the situation remains dire in other countries [2].Currently, there is no proven, effective antiviral therapy for COVID-19 patients.Identifying a drug that effectively reduces viral load may improve patient outcomes [11].New drug development takes time, and developing an antiviral drug speci cally for COVID-19 over the short term seems highly unlikely.Focusing on the potential of existing antiviral drugs is the most feasible strategy.Hence our willingness to share our experiences, in an effort to determine a potential anti-SARS-CoV-2 therapy.
In previous studies, lopinavir/ritonavir demonstrated in-vitro antiviral activity against SARS-CoV [7].Additionally, historical control groups demonstrated that compared to ribavirin monotherapy, a ribavirin and lopinavir/ritonavir combination reduced the risk of adverse outcomes in patients with SARS [7].However, Cao et al. [12] recently advised that no bene t was demonstrated when using lopinavir/ritonavir therapy, compared with other treatments in critical COVID-19 patients.Similarly, in this study, we failed to demonstrate any superiority in outcomes when using lopinavir/ritonavir monotherapy, in non-severe COVID-19 patients.This may be due to lopinavir/ritonavir not being speci c enough for COVID-19, or that high blood/tissue concentrations are required to inhibit the virus in-vivo.
Chloroquine has been used for more than 70 years, rstly as an anti-malarial drug and later for autoimmune diseases such as rheumatoid arthritis [13].Additionally, chloroquine has demonstrated antiviral effects by increasing endosomal pH, thus inhibiting endocytosis [13].Moreover, it inhibits viral replication by interfering with glycosylation of the angiotensin-converting enzyme 2 receptor of SARS-CoV, which the virus uses to enter the patient's cells [3,6].Huang et al. [14] found that COVID-19 patients had higher levels of pro-in ammatory cytokines in their plasma, which might induce a cytokine storm and immunopathological injury [15].Chloroquine is therefore bene cial in that it can demonstrate immunomodulatory effects, which may reduce complications due to an excessive immune response [16].In addition, Wang et al. [17] revealed that chloroquine could control SARS-CoV-2 infection in-vitro using a clinically achievable concentration in the plasma, further suggesting that chloroquine may be an effective antiviral therapy during the current outbreak.In our study, we found that chloroquine could reduce the viral load in patients early on, which theoretically should decrease the risk of viral transmission and improve the clinical outcomes of patients.With this being said, 2 patients experienced adverse effects during chloroquine therapy, and concern has previously been raised regarding its toxicity [18].Therefore, according to the announcements from the National Health Commission of China [9], a patient's electrocardiogram should be normal before commencing chloroquine therapy, and simultaneous administration of quinolone or macrolide antibiotics should be avoided in these patients.Furthermore, for improved safety, the duration of treatment could be shortened to 7 days, with close attention being paid to the patient for the duration of treatment, especially in patients with a lower weight (<50kg).
As a broad-spectrum antiviral agent, arbidol has demonstrated effectiveness in inhibiting certain respiratory viruses (in uenza virus, respiratory syncytial virus, etc.) including SARS-CoV in-vitro [8,19].Studies comparing arbidol and lopinavir/ritonavir combination therapy to lopinavir/ritonavir monotherapy in hospitalised, COVID-19 patients, found that the combination therapy group demonstrated an increase in negative SARS-CoV-2 tests by day 7 and day 14 with treatment [20].Similarly, in our study, the arbidol group showed a decreased shedding interval and an increase in negative SARS-CoV-2 tests at day 10 and at day 14.However, the exact mechanism of arbidol against SARS-CoV-2 has not been determined, thus requiring further study.Some limitations exist in our study.Firstly, it is a single-centred, small sample size study.Secondly, nucleic acid testing was only performed on upper respiratory tract specimens.Finally, the estimated interval of viral shedding is limited by the frequency of respiratory specimen collection, due to the retrospective study design.
In conclusion, our study revealed that chloroquine and arbidol (Umifenovir) could not only shorten the viral shedding interval, but also decreased the hospitalisation duration and hospitalisation expenses of non-severe, COVID-19 patients.Furthermore, we recommend that large randomised, controlled studies be conducted in the future to better understand the e cacy of various antiviral therapies, dosages and usage durations. Figures Clinical proceduresAll patients were diagnosed with COVID-19 in accordance with the Chinese COVID-2019 diagnosis and treatment guidelines[9].Upper respiratory tract specimens were obtained for a SARS-CoV-2 diagnosis according to the National Health Commission of China's laboratory testing techniques guidelines [10].A real-time reverse transcriptase polymerase chain reaction (RT-PCR) assay was used to detect the viral RNA of SARS-CoV-2 by targeting an open reading frame 1a/b (ORF1a/b) and nucleocapsid protein (N).De nitive diagnosis is based on both target ORF1a/b and N testing positive [10].