A snapshot of the ongoing clinical research on COVID-19

The pandemic of coronavirus disease 2019 (COVID-19) presents an unprecedented challenge to rapidly develop new diagnostic, preventive and therapeutic strategies. Currently, thousands of new COVID-19 patients are quickly enrolled in clinical studies. We aimed to investigate the characteristics of the COVID-19 studies registered in ClinicalTrials.gov and report the extent to which they have incorporated features that are desirable for generating high-quality evidence. On April 28, 2020, a total of 945 studies on COVID-19 have been registered in ClinicalTrials.gov; 586 studies are interventional (62.0%), the most frequent allocation scheme is the parallel group assignment (437; 74.6%), they are open-label and the most common primary purpose is the research on treatment. Too many of the ongoing interventional studies have a small expected sample size and may not generate credible evidence at completion. This might lead to a delayed recognition of effective therapies that are urgently needed, and a waste of time and resources. In the COVID-19 pandemic era, it is crucial that the adoption of new diagnostic, preventive and therapeutic strategies is based upon evidence coming from well-designed, adequately powered and carefully conducted clinical trials.

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Introduction
The pandemic of coronavirus disease 2019 (COVID-19) caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) presents an unprecedented challenge to rapidly develop new diagnostic, preventive and therapeutic strategies 1 . Currently, thousands of new COVID-19 patients present for care every day, and many are quickly enrolled in clinical studies. We aimed to investigate the characteristics of the COVID-19 studies registered in ClinicalTrials.gov 2 , and report the extent to which they have incorporated features that are desirable for generating high-quality evidence.

Methods
We investigated the ClinicalTrials.gov website on April 28, 2020, using the search term: SARS-

Discussion
Our survey presents the current COVID-19 clinical research landscape. Several hundreds of clinical studies have been initiated all over the globe, and the number is growing. Most interventional studies incorporate randomisation, which is considered the hallmark of high-quality clinical trials 3 , while more than 40% are blinded.
Studies are being conducted especially in the most affected areas: Europe and US. The number of COVID-19 cases in low to middle-income countries is still relatively low, also reflecting scarce testing, but is expected to rise in the next period. These countries will need more research on organizational measures, and trials on interventions that are affordable and applicable to those settings 4 .
Most studies focus on adults and elderlies, while only few target children, possibly reflecting the observed burden of the disease. Additional effort is needed to ensure that minors are included in COVID-19 clinical research, so that therapeutic decisions are based upon high-quality evidence.
No drug with proven clinical efficacy currently exists for SARS-CoV-2 infection. Despite the absence of solid evidence, several treatments are being currently used in clinical practice in several countries, with sometimes disastrous consequences 5 . Too many of the ongoing interventional studies have a small expected sample size, and may not generate credible evidence at completion 4 . This might lead to a delayed recognition of effective therapies that are urgently needed, and a waste of time and resources. In the COVID-19 pandemic era, it is crucial that the adoption of new diagnostic, preventive and therapeutic strategies is based upon evidence coming from well-designed, adequately powered and carefully conducted clinical trials.

Data availability
The Clinical Trials website can be accessed here: https:// clinicaltrials.gov/

Department of Health Sciences, School of Sciences, European University Cyprus, Nicosia, Cyprus
This brief report is a survey of the current COVID-19 clinical research landscape. The number of clinical studies on COVID-19 is rapidly growing and it is important the investigation of whether these studies are incorporating features that are desirable for generating high-quality evidence. This survey performed this investigation and found that too many of the ongoing interventional studies have a small expected sample size. This might lead to delayed recognition of effective therapies and a waste of time and resources. This important evidence should guide the design of any future clinical study on COVID-19 and the decision of any funding body as well as the approval of any bioethics committee. For this reason, I consider this brief report important for the scientific community.
There are a few minor suggestions for the authors: Table 1: The presentation of the studies' characteristics will be improved if they are presented separately for interventional and observational studies (particularly for the intervention type and expected study size). In this way, the table will provide more information about the studies' characteristics for each study type (interventional and observational). Table 1: It will be useful to report the type of randomization (such as blocking and block size).

Is the work clearly and accurately presented and does it cite the current literature? Yes
Is the study design appropriate and is the work technically sound? Yes

If applicable, is the statistical analysis and its interpretation appropriate? Not applicable
Are all the source data underlying the results available to ensure full reproducibility? Yes Are the conclusions drawn adequately supported by the results? Yes No competing interests were disclosed. Competing Interests: Reviewer Expertise: Epidemiology, Statistics, Research Methods, Public Health I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard.
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