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* primary studies on COVID-19, including interventional, observational, diagnostic, prognostic, epidemiological and qualitative 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 display study records which contain one or more references for that study. Export files contain all the references, meaning export files 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, with other study designs to follow.

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

Where do we source our references?

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.  

Data sources for Cochrane's COVID-19 Study Register currently include:

We also monitor Retraction Watch daily. Retraction notices and expressions of concerns are added as references and linked to studies in the register.

** Search tip: To retrieve Embase.com references, conduct a search for the database name with an asterisk: Embase*  

How frequently is the register updated? 

We update PubMed and ClinicalTrials.gov records daily (Monday-Friday); Embase, ICTRP and medRxiv records weekly; and CENTRAL records monthly (after CENTRAL publishes at the end of each month). Please note: there is an approximate delay of 48 hours before evaluation of PubMed records. 

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 31 March 2021)


(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 "COVID-19"[Mesh] OR "COVID-19 Testing"[Mesh] OR "COVID-19 Vaccines"[Mesh] OR "Coronavirus"[Mesh:NoExp] OR "Receptors, Coronavirus"[Mesh] OR "SARS-CoV-2"[Mesh] OR "Spike Glycoprotein, Coronavirus"[Mesh]) NOT ("animals"[mh] NOT "humans"[mh]) NOT (editorial[pt] OR newspaper article[pt])


((('anti-SARS-CoV-2 agent'/exp OR 'coronaviridae'/de OR 'coronavirinae'/de OR 'coronaviridae infection'/de OR 'coronavirus disease 2019'/exp OR 'coronavirus infection'/de OR 'COVID-19 testing'/exp OR 'sars coronavirus 2 test kit'/exp 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


1 ("2019 nCoV" OR 2019nCoV OR "corona virus*" OR coronavirus* OR COVID OR COVID19 OR "nCov 2019" OR "SARS-CoV2" OR "SARS CoV-2" OR SARSCoV2 OR "SARSCoV-2"):TI,AB AND CENTRAL:TARGET



4 #1 OR #2 OR #3


6 #5 AND #4


8 #6 NOT #7 


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


COVID OR 2019-nCoV OR SARS-CoV-2 OR coronavirus OR corona virus

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:

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.


The National Library of Medicine is the source of PubMed bibliographic records.

Embase.com records are provided under license by Elsevier. All rights are retained by the license holder.

Trial registry records are sourced from ClinicalTrials.gov and the World Health Organization's International Clinical Trial Registry Platform (ICTRP).

medRxiv preprint records are sourced from Cold Spring Harbor Laboratory, BMJ, Yale. We acknowledge the Stephen B. Thacker CDC Library for compiling and providing the medRxiv preprint records.

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: March 31, 2021