Overview:

This map consists of studies on COVID-19, identified in MEDLINE and Embase, and published in 2019 or later. To check that you are viewing the latest version, please visit https://eppi.ioe.ac.uk/cms/Projects/DepartmentofHealthandSocialCare/Publishedreviews/COVID-19Livingsystematicmapoftheevidence/tabid/3765/Default.aspx

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 began searching MEDLINE and Embase, on Wednesday 4th March, 2020, and we have continued to run a weekly search, updating the search strategy, as necessary.

The MEDLINE search strategy is the OVID Expert Search as developed by Wolters Kluwer and available at http://tools.ovid.com/coronavirus/

MEDLINE search strategy as at 21st April 2020

1 exp Coronavirus/
2 exp Coronavirus Infections/

3 (coronavirus* or corona virus* or OC43 or NL63 or 229E or HKU1 or HCoV* or ncov* or covid* or sars-cov* or sarscov* or Sars-coronavirus* or Severe Acute Respiratory Syndrome Coronavirus*).mp.

4 (or/1-3) and ((20191* or 202*).dp. or 20190101:20301231.(ep).)

5 4 not (SARS or SARS-CoV or MERS or MERS-CoV or Middle East respiratory syndrome or camel* or dromedar* or equine or coronary or coronal or covidence* or covidien or influenza virus or HIV or bovine or calves or TGEV or feline or porcine or BCoV or PED or PEDV or PDCoV or FIPV or FCoV or SADS-CoV or canine or CCov or zoonotic or avian influenza or H1N1 or H5N1 or H5N6 or IBV or murine corona*).mp.

6 ((pneumonia or covid* or coronavirus* or corona virus* or ncov* or 2019-ncov or sars*).mp. or exp pneumonia/) and Wuhan.mp.

7 (2019-ncov or ncov19 or ncov-19 or 2019-novel CoV or sars-cov2 or sars-cov-2 or sarscov2 or sarscov-2 or Sars-coronavirus2 or Sars-coronavirus-2 or SARS-like coronavirus* or coronavirus-19 or covid19 or covid-19 or covid 2019 or ((novel or new or nouveau) adj2 (CoV on nCoV or covid or coronavirus* or corona virus or Pandemi*2)) or ((covid or covid19 or covid-19) and pandemic*2) or (coronavirus* and pneumonia)).mp.

8 COVID-19.rx,px,ox. or severe acute respiratory syndrome coronavirus 2.os.

9 ("32240632" or "32236488" or "32268021" or "32267941" or "32169616" or "32267649" or "32267499" or "32267344" or "32248853" or "32246156" or "32243118" or "32240583" or "32237674" or "32234725" or "32173381" or "32227595" or "32185863" or "32221979" or "32213260" or "32205350" or "32202721" or "32197097" or "32196032" or "32188729" or "32176889" or "32088947" or "32277065" or "32273472" or "32273444" or "32145185" or "31917786" or "32267384" or "32265186" or "32253187" or "32265567" or "32231286" or "32105468" or "32179788" or "32152361" or "32152148" or "32140676" or "32053580" or "32029604" or "32127714" or "32047315" or "32020111" or "32267950" or "32249952" or "32172715").ui.

10 or/6-9

11 5 or 10

The Embase search strategy as at 21st April 2020

1 exp Coronavirus Infections/
2 exp coronavirinae/

3 (coronavirus* or corona virus* or OC43 or NL63 or 229E or HKU1 or HCoV* or ncov* or covid* or sars-cov* or sarscov* or Sars-coronavirus* or Severe Acute Respiratory Syndrome Coronavirus*).mp.

4 or/1-3

5 4 not (SARS or SARS-CoV or MERS or MERS-CoV or Middle East respiratory syndrome or camel* or dromedar* or equine or coronary or coronal or covidence* or covidien or influenza virus or HIV or bovine or calves or TGEV or feline or porcine or BCoV or PED or PEDV or PDCoV or FIPV or FCoV or SADS-CoV or canine or CCov or zoonotic or avian influenza or H1N1 or H5N1 or H5N6 or IBV or murine corona*).mp.

6 ((pneumonia or covid* or coronavirus* or corona virus* or ncov* or 2019-ncov or sars*).mp. or exp pneumonia/) and Wuhan.mp.

7 (2019-ncov or ncov19 or ncov-19 or 2019-novel CoV or sars-cov2 or sars-cov-2 or sarscov2 or sarscov-2 or Sars-coronavirus2 or Sars-coronavirus-2 or SARS-like coronavirus* or coronavirus-19 or covid19 or covid-19 or covid 2019 or ((novel or new or nouveau) adj2 (CoV on nCoV or covid or coronavirus* or corona virus or Pandemi*2)) or ((covid or covid19 or covid-19) and pandemic*2) or (coronavirus* and pneumonia)).mp.

8 6 or 7

9 5 or 8

On 29th June a new duplicate algorithm found several duplicates in earlier searches, so the numbers in each search have changed.
The first searches (MEDLINE and Embase) identified 1,305 records, after removing duplicates; 254 were excluded by publication date, and 19 more as duplicates, leaving 1,044 to be coded. Of these, 177 were excluded as not on topic; one further duplicate was found; 585 records were excluded (other viruses or not primary data); and 269 records are now in the map.

The second searches, on 18th March, identified 592 new records. Of the new records, 23 were not on topic, two further duplicates were removed, 327 records were excluded (other viruses or not primary data), and 240 records are in the map.

The third searches, on 24th March, identified 338 new records; 19 were not on topic, 218 records were excluded, and 101 records are in the map.

The fourth searches, on 31st March, identified 641 records, after duplicates had been removed; 22 were not on topic, 424 records were excluded, and 195 records are in the map.

The fifth search, on 7th April, identified 1,046 new records; 48 were not on topic, one further duplicate was removed, 685 records were excluded, and 312 records are in the map. The code definitions were adapted, and the codes were changed for six records (most were moved from health impacts to treatment development).

The sixth search, on 14th April, identified 1,154 new records; 66 were not on topic, 750 records were excluded, and 338 records are in the map.

The seventh search, on 21st April, identified 1,807 new records; 84 were not on topic, one was a duplicate, 1,130 records were excluded, and 592 records are in the map.
The eighth search, on 28th April, identified 1,360 new records, 59 were not on topic, 895 records were excluded, and 406 records are in the map.
The ninth search, on 4th May, identified 1,071 new records, 48 were not on topic, 700 were excluded, and 323 are in the map.
The tenth search, on 11th May, identified 2,352 new records, 92 were not on topic, 1,448 were excluded, and 812 are in the map.
The eleventh search, on 18th May, identified 3,161 new records, 129 were not on topic, 1,940 were excluded, and 1,092 are in the map.
The twelfth search, on 25th May, identified 2,629 new records, 140 were not on topic, 1,529 were excluded, and 959 are in the map.
The thirteenth search, on 1st June, identified 2,411 new records, 213 were not on topic, 1,372 were excluded, and 826 are in the map.
The fourteenth search, on 8th June, identified 2,572 new records, 160 were not on topic, 1,443 were excluded, and 969 are in the map.
The fifteenth search, on 15th June, identified 2,838 new records, 141 were not on topic, 1,452 were excluded, and 1,245 are in the map.
The sixteenth search, on 22nd June, identified 2,437 new records, 126 were not on topic, 1,474 were excluded, and 886 are in the map.
The seventeenth search, on 29th June, identified 2,610 new records, 146 were not on topic, 1,448 were excluded, and 1,016 are in the map.

Coding the evidence:

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

Primary empirical data, systematic review*, modelling** or novel analysis on COVID-19
1. Treatment evaluation
  - - Clinical interventions (treatments or vaccines)
  - - Prospective outcome studies with at least some data from before and after an intervention
  - - Exclude observational / retrospective studies including treatment as an exposure (code as ‘treatment development’)
  - - Exclude case reports with some information about treatment (code as ‘case reports’)
  - - Exclude basic 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 (incl. studies which aim to model mortality, health outcomes or health system outcomes)
  - - Risk modelling
  - - Studies of viral persistence in bodily secretions / tissues or in the environment, e.g., on surfaces (including methods to inactivate the virus in these contexts)
  - - Population prevalence studies
  - - Studies of risk factors for developing COVID-19 at individual level (not risks of developing more severe disease/complications among people infected with COVID-19; code as ‘health impacts’) or at population level
  - - Studies of the effectiveness of prevention strategies, e.g., masks, contact tracing (only if data on prevalence reported)
3. Diagnosis
  - - Sensitivity and specificity of tests
  - - Modelling/evaluation of screening or testing programmes, or training clinicians in diagnosis
  - - 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 studies reporting prevalence data here if they also present health impacts). Include studies of prognostic factors, indicators of disease progress or severity. Include case series if they have more than a small number of patients and report descriptive statistics. Include indirect health impacts on healthcare workers (e.g. from PPE use).
5. Vaccine development
  - - Basic science aimed at development of vaccines
6. Treatment development
  - - Basic science aimed at development of treatments, e.g., drug discovery
  - - Studies looking at treatments but not meeting methodological criteria for ‘treatment evaluation’, e.g., observational / retrospective studies including treatment as an exposure (but exclude studies of outcomes which simply state that treatment was administered without relating outcomes to treatments – code under ‘health impacts’)
  - - Studies of treatment safety / side-effects
  - - Training clinicians to deliver interventions
  - - (Studies of relevance to both vaccine and treatment development – code under ‘treatment development’)
7. Genetics / biology of virus
  - - Any data on the genetic or biological characteristics of the virus, or of mechanisms or responses to infection (including antibody responses, if not clearly aimed at diagnosis/vaccine development)
  - - Include modelling on the basis of secondary data analysis
  - - Exclude studies of biological mechanisms theoretically linked to COVID-19 infection, but without data which actually concern COVID-19
  - - If explicitly aimed at treatment (resp. vaccine) development, code as ‘treatment development’ resp. ‘vaccine development’
8. Case reports - patients
  - - Medical case reports of small numbers of patients, considered as individuals
  - - Include any case with confirmed COVID-19 or symptoms or history suggestive of COVID-19 infection (otherwise code as ‘not on topic’; case studies of health professionals and mental health consequences of lockdown are also not on topic)
9. Case study – organisation
  - - Descriptive studies setting out organisational responses / strategies to COVID-19
  - - Surveys of professionals/institutions on organisational responses (not broader knowledge or attitudes to COVID-19 – code these as ‘social and economic impacts’)
  - - Include any organisation (healthcare or other) and any form of response to COVID-19, whether directly concerning COVID-19 patients or not
  - - Exclude guidance or recommendation papers which do not describe the recommended measures being implemented in a specific case
10. Social and economic impacts
  - - Include studies mainly focusing on behaviour, attitudes etc.
  - - Studies of information (e.g., analysis of websites or social media)
  - - Surveys of professionals, if not mainly focused on organisational responses
  - - Studies of behaviour or health outcomes of patients without diagnosed COVID-19
11. Mental health impacts

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

Two exclude codes were originally included in the map, but from 21st April, 2020 these are no longer shown.

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.
- - Protocols for studies or reviews which do not report findings data
- - Systematic reviews which do not report findings data (mapping reviews; reviews which only contain guideline documents / opinion pieces)
- - Methods papers (including validation of data collection methods, if usable primary data not reported)

To access a ris file for either or both of these codes, please email theo.lorenc@york.ac.uk

Suggested citation:

Lorenc T, Khouja C, Raine G, Sutcliffe K, Shemilt I, Kwan I, Thomas S, 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