About COVID-19 Study Register

What is the Cochrane COVID-19 Study Register?

The Cochrane COVID-19 Study Register is a freely-available, continually-updated, annotated reference collection of human studies* on COVID-19, including interventional, observational, diagnostic, prognostic, epidemiological, qualitative and economic designs.

Cochrane's COVID-19 Study Register is "study-based," meaning references to the same study (e.g. press releases, trial registry records, preprints, journal pre-proofs, journal articles, retraction notices and expressions of concern) are all linked to a single study record. Search results will display study records which contain one or more references for that study. Export files will contain all the references, which is why export may contain more records that search results. Tip: In the .csv export file, sort by the column "CRS Study record ID" to bring all the references for the same study together.  

The aim of the register is to support rapid evidence synthesis, including Cochrane's work on Rapid Reviews in response to COVID-19.

To enable discovery, we add vocabulary descriptors to references from Cochrane's PICO ontology. Please note: PICO annotations are available initially for interventional studies and randomized controlled trials, with other study designs to follow.

* Note: the register does not include in-vitro study references.   

Where do we source our references?

Data sources for Cochrane's COVID-19 Study Register currently include ClinicalTrials.gov, WHO's International Clinical Trials Registry Platform (ICTRP), the National Library of Medicine's bibliographic database PubMed, medRxiv and Embase.com. We also monitor Retraction Watch daily. Retraction notices and expressions of concerns are added as references and linked to studies in the register.

We are currently adding unique COVID-19 references from Embase.com, provided under license from Elsevier. We expect these records to be fully incorporated into the register by the end of October. To retrieve Embase.com references, conduct a search for the database name with an asterisk (as below):


We are constantly evaluating new sources of COVID-19 study references and will update our list of sources as new references are included in the register.  

How frequently is the register updated? 

Currently, we are updating ClinicalTrials.gov and PubMed records daily (Monday-Friday), ICTRP records weekly (on Fridays), and medRxiv and Embase.com records weekly (on Mondays). 

What are our search methods? 

Search Strategies: Search strategies are designed for maximum sensitivity, to retrieve all human studies on COVID-19. No language limits are applied. Strategies will be updated to account for changes to the COVID-19 study register's eligibility criteria, changes to database interfaces and ongoing search performance assessments. Please contact us to request previous versions of the strategies and the dates they were implemented. 

The PubMed strategy was designed by Robin Featherstone MLIS, Information Specialist Cochrane Editorial and Methods Department, and peer reviewed by Douglas Salzwedel MLIS, Information Specialist and Assistant Managing Editor Cochrane Hypertension. The current PubMed search was validated on Aug 9 against a "gold standard" sample of 184 known PubMed study references on COVID-19. Sensitivity was 1.0 (i.e. all references in the sample were retrieved). 

The Embase.com strategy was designed by Robin Featherstone and peer reviewed by Julie Glanville MSc, Independent Consultant and Co-Convenor, Cochrane Information Retrieval Methods Group. The Embase.com strategy was validated on Aug 12 with a sensitivity of 1.0 using a sample of 177 known Embase study references on COVID-19.


Current Strategy (last updated 17 Aug 2020)


COVID-19 OR 2019-nCoV OR SARS-CoV-2 OR coronavirus


We screen the entire COVID-19.csv file available from https://www.who.int/emergencies/diseases/novel-coronavirus-2019


(2019 nCoV[tiab] OR 2019nCoV[tiab] OR corona virus[tiab] OR corona viruses[tiab] OR coronavirus[tiab] OR coronaviruses[tiab] OR COVID[tiab] OR COVID19[tiab] OR nCov 2019[tiab] OR SARS-CoV2[tiab] OR SARS CoV-2[tiab] OR SARSCoV2[tiab] OR SARSCoV-2[tiab] OR "Coronavirus"[Mesh:NoExp] OR "COVID-19"[nm] OR "COVID-19 drug treatment"[nm] OR "COVID-19 diagnostic testing"[nm] OR "COVID-19 serotherapy"[nm] OR "COVID-19 vaccine"[nm] OR "LAMP assay"[nm] OR "severe acute respiratory syndrome coronavirus 2"[nm] OR "spike protein, SARS-CoV-2"[nm]) NOT ("animals"[mh] NOT "humans"[mh]) NOT (editorial[pt] OR newspaper article[pt])


((('coronaviridae'/de OR 'coronavirinae'/de OR 'coronaviridae infection'/de OR 'coronavirus disease 2019'/exp OR 'coronavirus infection'/de OR 'SARS-related coronavirus'/de OR 'Severe acute respiratory syndrome coronavirus 2'/exp OR '2019 nCoV':ti,ab,kw OR 2019nCoV:ti,ab,kw OR ((corona* OR corono*) NEAR/1 (virus* OR viral* OR virinae*)):ti,ab,kw OR coronavir*:ti,ab,kw OR coronovir*:ti,ab,kw OR COVID:ti,ab,kw OR COVID19:ti,ab,kw OR HCoV*:ti,ab,kw OR 'nCov 2019':ti,ab,kw OR 'SARS CoV2':ti,ab,kw OR 'SARS CoV 2':ti,ab,kw OR SARSCoV2:ti,ab,kw OR 'SARSCoV 2':ti,ab,kw) NOT (('animal experiment'/de OR 'animal'/exp) NOT ('human'/exp OR 'human experiment'/de))) NOT 'editorial'/it) NOT ([medline]/lim OR [pubmed-not-medline]/lim) AND [1-12-2019]/sd

medRxiv We screen the entire COVID-19 results identified by the Stephen B. Thacker CDC Library

How do we define our study aims? 

To enable filtering of search results, we add study aims to references in the Cochrane COVID-19 Study Register. Study aim definitions are below:

Diagnosis/prognosis: where the study aims to understand the signs and symptoms of a condition or disease, to assess the accuracy of a test in diagnosing a condition/disease, or to predict a certain outcome (prognosis).

Epidemiology: where the study aims to look at the incidence, distribution, and possible control of the virus at a population level.

Health services research: where the study aims to evaluate the delivery, processes, management, organization, or financing of healthcare.

Mechanism: where the study aims to examine the possible underlying causes of the COVID-19 infection, the pathophysiology of COVID-19, or the mechanism of action of drugs being trialed for the prevention or treatment of COVID-19

Other: where the study aims don’t meet any of the other aims. One example might be a study looking at the mental health effects of students not able to take their exams during the pandemic, or another example is a study looking at the treatment and management of health conditions other than COVID-19 during the pandemic.

Prevention: where the study aims to assess one or more interventions for preventing the development of a specific disease or health condition.

Transmission: where the study aims to estimate or calculate the spread of the virus as well as those that look at specific characteristics and cases of transmission (passing on of the virus) between people.

Treatment and management: where the study aims to evaluate treatment or management intervention for a specific health condition to treat, maximize comfort, or alleviate symptoms or side effects. It could be a drug or surgery or a non-pharmacological (non-drug) therapy like light or music therapy.


Trial registry records are sourced from ClinicalTrials.gov and the World Health Organization's International Clinical Trial Registry Platform (ICTRP). The National Library of Medicine is the source of PubMed bibliographic records; and Cold Spring Harbor Laboratory, BMJ, Yale are the source of medRxiv preprint records. We acknowledge the Stephen B. Thacker CDC Library for compiling and providing the medRxiv preprint records. Embase.com records are provided under license by Elsevier. All rights are retained by the license holder.

Our development partners are Data Language and Metaxis

Notes on Modifications

Study design characteristics and controlled vocabulary descriptors are added to source records to enable advanced search features.

Terms and Conditions of Use / Disclaimer

All persons reproducing, redistributing, or making commercial use of this information are expected to adhere to the terms and conditions asserted by the copyright holder. Transmission or reproduction of protected items beyond that allowed by fair use as defined in the copyright laws requires the written permission of the copyright owners.

Cochrane does not warrant or assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed.


Please direct any questions or comments about Cochrane's COVID-19 Study Register to covid-19-register@cochrane.org


Page last updated: October 9, 2020