Overview:

This map consists of studies on COVID-19, identified in MEDLINE and Embase, and published in 2019 or later.

Using this map:

There are various ways to use the map.

The size of the circles, or the number of tiles in mosaic view, is proportional to the number of references in the cell. To view these references, click on the cell of interest. You can also click on a column or row header to view all the references relating to that row or column.

To view the full set of references, click on the 'Reader' tab above the map. Further details about the studies can be found by clicking on the URL and exploring the full text, where available.

It may appear as though there are no studies in a cell; hover the cursor over the cell to see how many studies are actually in that cell. In the filters tab, change the view to mosaic to more easily see the number of studies in each cell.

Identifying the evidence:

We searched MEDLINE and Embase, on Wednesday 4th March, 2020, and we are updating this every week.

MEDLINE search strategy for 4th March, 2020

1 (exp coronavirus/ or coronavirus*.mp.) and (wuhan or beijing or shanghai or 2019-nCoV or nCoV or COVID-19 or SARS-CoV-2).mp. (492)

2 coronavirus*.ti. or (novel coronavirus*.mp. and (exp china/ or china.mp.)) or ((pneumonia.mp. or exp pneumonia/) and Wuhan.mp.) (6712)

3 ("COVID-19" or "2019-nCoV" or "SARS-CoV-2").mp. or exp Coronavirus Infections/ (9928)

4 2 or 3 (13485)

5 (201912$ or 2020$).dt. (339475)

6 4 and 5 (777)

7 1 or 6 (883)

The first Embase search identified 1,080 records, of which 658 were duplicates. After deduplication, there were 1,305 records; 255 were excluded by publication date; one further duplicate was identified; and 177 were excluded as not on topic; leaving 872 records to be coded.

The second searches, on 18th March, identified 596 records, after removing duplicates. Four additional duplicates were found within the first search results, leaving 868 in the first search. Of the new records, 23 were not on topic, and 573 were coded.

The third searches, on 24th March, identified 348 new records, after duplicates had been removed; 19 were not on topic, six were published before 2019, and 323 were coded. Three additional duplicates were removed from the second search, leaving 570 in the second search.

The fourth searches, on 31st March, identified 643 records, after duplicates had been removed; 25 were not on topic, and 618 were coded.

Coding the evidence:

The definitions for inclusion in the category headings are as follows.

Primary empirical data, systematic review* or modelling on COVID-19
1. Intervention
  - - Outcome studies with at least some data from before and after an intervention (i.e. before-after studies, trials)
  - - Exclude observational / retrospective studies including treatment as an exposure (code as ‘health impacts’)
  - - NB. Exclude case reports with some information about treatment (code as ‘case reports’)
  - - NB. Exclude lab science with claimed relevance to interventions, but without evaluation of effectiveness in human patients (code as ‘treatment development’ or ‘vaccine development’)
2. Transmission / risk / prevalence
  - - Epidemiological modelling of spread
  - - Risk modelling
  - - Basic / lab science on mechanisms of infection, including studies of viral persistence in bodily secretions / tissues
  - - Population prevalence studies
  - - NB. If studies present data on both prevalence and health impacts, code under ‘health impacts’
3. Diagnosis
  - - Testing
  - - Modelling of screening programmes
  - - Include studies of clinical signs if the main focus is on their diagnostic value (if the focus is on health outcomes or prognosis, code under ‘health impacts’)
4. Health impacts of COVID-19
  - - Any study with a population of COVID-19-infected patients measuring physical health outcomes (incl. mortality) and/or somatic indicators (code transmission / prevalence studies here if they also present health impacts). Include studies of prognostic factors. Include case series if they have more than a small number of patients and report descriptive statistics.
5. Vaccine development
  - - Any data including lab studies / animal studies etc.
6. Treatment development
  - - Any data including lab studies / animal studies etc. (Studies of relevance to both vaccine and treatment development – code under ‘treatment development’)
  - - Exclude studies looking at treatment outcomes (code as either ‘intervention’ or ‘health impact’ depending on methodology)
7. Genetics / biology of virus
  - - Any data on the genetic or biological characteristics of the virus
  - - Include modelling on the basis of secondary data analysis
8. Case reports - patients
  - - Medical case reports of small numbers of patients, not in other categories
9. Case study – organisation
  - - Descriptive studies setting out organisational responses / strategies
10. Social and economic impacts
  - - Include studies mainly focusing on behaviour, attitudes etc.
11. Mental health impacts
Exclude - other viruses (SARS, MERS, etc.)
- - Anything on human coronaviruses other than COVID-19; include both primary data and non-data papers
Exclude - no primary empirical data, systematic review or modelling
- - Include thinkpieces, non-systematic reviews, guidance, consensus statements etc.

* Define ‘systematic review’ as any paper reporting secondary data which reports both some search terms and clearly defined inclusion criteria.

Suggested citation:

Lorenc T, Khouja C, Raine G, Sutcliffe K, Wright K, Sowden A, Thomas J (2020) COVID-19: living map of the evidence. London: EPPI-Centre, Social Science Research Unit, UCL Institute of Education, University College London.

Funding:

This map was commissioned by the National Institute for Health Research (NIHR) Policy Research Programme (PRP) for the Department of Health and Social Care (DHSC) and Public Health England (PHE). It was funded through the NIHR PRP contract with the EPPI Centre at UCL (Reviews facility to support national policy development and implementation, PR-R6-0113-11003). Any views expressed in this publication are those of the author(s) and not necessarily those of the NHS, the NIHR or the DHSC.

Conflicts of interest:

There were no conflicts of interest in the writing of this report.

Contributions:

Any opinions expressed in this publication are not necessarily those of the EPPI-Centre or the funders. Responsibility for any views expressed remains solely with the authors.

(c) Copyright:

Authors of the systematic reviews on the EPPI-Centre website http://eppi.ioe.ac.uk hold the copyright for the text of their reviews. The EPPI-Centre owns the copyright for all material on the website it has developed, including the contents of the databases, manuals, and keywording and data-extraction systems. The centre and authors give permission for users of the site to display and print the contents of the site for their own noncommercial use, providing that the materials are not modified, copyright and other proprietary notices contained in the materials are retained, and the source of the material is cited clearly following the citation details provided. Otherwise users are not permitted to duplicate, reproduce, re-publish, distribute, or store material from this website without express written permission.

The NIHR Policy Research Programme, Reviews Facility is a collaboration between the following:

UCL Institute of Education

EPPI-Centre (Evidence for Policy and Practice Information and Co-ordinating Centre)

London School of Hygiene & Tropical Medicine

University of York Centre for Reviews and Dissemination