Keep updated – searching the literature on COVID-19
The research on COVID-19 is rapidly evolving, thus a moving object and difficult to summarize. Results are published on a daily basis – from ongoing research and preprints to clinical studies and literature reviews. From unfiltered to filtered information.
LitCovid – curated literature from Pubmed on COVID-19
LitCovid, hosted by National Library of Medicine (NLM), is a curated literature hub for tracking up-to-date scientific information about the 2019 novel Coronavirus. All data is collected from Pubmed, but LitCovid offers unique categorization for research topics and geographic locations.
The initiative was launched in a Nature article in March 2020.
WHO Global literature on coronavirus disease
WHO is gathering the latest international multilingual scientific findings and knowledge on COVID-19. The global literature cited in the WHO COVID-19 database is updated daily (Monday through Friday) from searches of bibliographic databases, hand searching, and the addition of other expert-referred scientific articles.
General Personal & protective equipment Pregnancy Paediatrics
As often, Pubmed is a good starting point for the biomedical literature. It is also an open and freely accessible database for all, not just for students and researchers affiliated to universities.
If we start simple and just type covid-19 in the search box, Pubmed will automatically map this phrase (important to not use quotation marks) to a validated search filter:
- "COVID-19"[All Fields] OR "COVID-2019"[All Fields] OR "severe acute respiratory syndrome coronavirus 2"[Supplementary Concept] OR "severe acute respiratory syndrome coronavirus 2"[All Fields] OR "2019-nCoV"[All Fields] OR "SARS-CoV-2"[All Fields] OR "2019nCoV"[All Fields] OR (("Wuhan"[All Fields] AND ("coronavirus"[MeSH Terms] OR "coronavirus"[All Fields])) AND (2019/12[PDAT] OR 2020[PDAT]))
As we can see, many additional terms are added, as well as geographical terms and a date limit from December 2019 (when the new virus was discovered).
Medical Subject Headings (MeSH)
And for the general concept of coronavirus, there are two MeSH terms:
These two, including more specific terms in the hierarchical structure, were introduced in MeSH in 1994.
Please bear in mind that the indexing of articles with MeSH terms in Pubmed have a time lag, sometimes up to a year. This means that if you limit your search to MeSH terms in the MeSH search field only, the most recent studies will be excluded. This also applies to some of the Filters in the left menu in Pubmed. For instance, if you limit your result to Age or Publication Type, new references will be excluded. In sum, avoid these filters.
Follow these steps in Pubmed:
- Conduct a search, for example using the live searches below.
- Click on Create alert.
- Log in using your NCBI account. If you need to create one first, click other login options and Sign up.
- Name your search and set frequency etc.
- Click on Save.
A great web resource, developed by the Australian Library and Information Association, provides automatic Pubmed searches on a range of COVID-19 topics, for example on prevention, diagnostics and population:
Medical Library Association (MLA) also lists and links search strategies on COVID-19 in Pubmed:
In addition to Pubmed, Embase is an important biomedical database with a focus on farmacology and toxicology. Embase also includes a large amount of conference materials and more European journals than Pubmed. Unfortunately, Embase is not open for all and a subscription is needed for access.
Search for COVID-19 in Embase:
- Go to Embase login (for students and staff at KI)
- Click on the Results menu.
- Copy and paste the following search strategy:
('covid 19'/exp OR 'coronavirus disease 2019'/exp OR 'covid 19':ti,ab OR ((covid NEAR/2 19):ti,ab) OR ((sars NEAR/2 'cov 2'):ti,ab) OR '2019 ncov':ti,ab OR ((wuhan:ti,ab OR hubei:ti,ab) AND coronavirus*:ti,ab) OR ([2019-2020]/py AND (new:ti,ab OR novel:ti,ab OR pandemic:ti,ab OR epidemic:ti,ab) AND ('coronavirus infection'/exp OR coronavirus*:ti,ab OR 'corona virus*':ti,ab)))
Google Scholar is an excellent resource the check the latest research on COVID-19. The content is broader in scope than Pubmed and covers more differentiated publication types. To some extent, the content is also searched in full text – in comparison to traditional bibliographic databases like Pubmed. It is, however, tricky to perform a more structured and comprehensive search in Google Scholar and the search result often generates thousands of hits.
The following search strategy is developed for Google Scholar:
- 2019 novel coronavirus disease OR 2019 novel coronavirus infection OR 2019-ncov disease OR 2019-ncov infection OR coronavirus disease 2019 OR coronavirus disease-19 OR coronavirus* OR coronovirus* OR coronavirus Infections OR Wuhan coronavirus OR 2019-nCoV
- Live search in Google Scholar
Web of Science
In addition to PubMed and Embase, the database Web of Science (Core Collection) is an excellent choice. It is a multidisciplinary source, thus interesting for COVID-19 searches in other scientific fields. Also, Web of Science includes citation data for discovery and metrics (for instance the most cited COVID-19 publications).
- Log on to Web of Science (for students and staff at KI)
- Click on the Advanced Search.
- Copy and paste the following search strategy:
TS=(coronavirus* OR "corona virus*" OR covid* OR ncov OR sars-cov* OR sarscov* OR 2019ncov) AND PY=2020
Medline via Ovid
A search strategy for COVID-19 is provided by Ovid (direct links under Expert Searches). As we can see, a quite comprehensive and intricate search filter (updated April 14, 2020). Also available as a limit.
- exp Coronavirus/
- exp Coronavirus Infections/
- (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.
- (or/1-3) and ((20191* or 202*).dp. or 20190101:20301231.(ep).) [this set is the sensitive/broad part of the search]
- 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. [line 5 removes noise in the search results]
- ((pneumonia or covid* or coronavirus* or corona virus* or ncov* or 2019-ncov or sars*).mp. or exp pneumonia/) and Wuhan.mp.
- (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 or 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.
- COVID-19.rx,px,ox. or severe acute respiratory syndrome coronavirus 2.os.
- ("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. [Articles not captured by this search when created in April 2020, pending further indexing by NLM]
- or/6-9 [Lines 6 to 9 are specific to Covid-19]
- 5 or 10
- 11 and 20191201:20301231.(dt).
For a more simple but still sensitive search strategy, we suggest:
- exp Coronavirus/
- exp Coronavirus Infections/
- (coronavirus* OR corona virus* OR covid* OR ncov OR sars-cov* OR sarscov* OR 2019ncov).mp.
- 3 and 20191201:20201231.(dt).
In line 3, we are using the field tag .mp. (instead of .ti,ab,kf.) for including Supplementary Concepts. Quotation marks are not needed in Ovid.
It is a challenge to stay updated with all new published studies, especially for clinicans with a high workload these days. Thankfully, there are several excellent resources that collects, appraise and synthesise the research on COVID-19.
The Centre for Evidence-Based Medicine at the University of Oxford publishes reviews of different topics concerning COVID-19 on a daily basis:
Cochrane have created a COVID-19 resources portal. Traditional Cochrane Reviews are very comprehensive and takes a long time to produce. To speed up the process during the pandemic, Cochrane have launched several initiatives, for example a methodology for Rapid Reviews:
An interesting and newly launched database is COVID-evidence.org, initiated by the University of Basel and Meta-Research Innovation Center at Stanford et al:
Protocols and preprints
The developments concerning COVID-19 is a rapidly evolving situation. The traditional process for publishing research is not always quick enough to translate research into clinical praxis. On the other hand, published studies need to be of high quality and to some extent peer reviewed.
Many clinical trials are registered at ClinicalTrials.gov and as of today approximately 500 COVID-19 related trials are ongoing:
Preprints – i.e. versions of manuscripts posted on public servers prior to peer review – can be important for getting updated on the latest research. It is, however, very important to know that these preprints are not peer-reviewed before being posted online. In biomedicine, medRxiv and bioRxiv, hosted by Cold Spring Harbor Laboratory, established online archives:
As always, stay updated on Retraction Watch, a blog that reports on retractions of scientific papers and related topics. For example Elsevier investigating hydroxychloroquine-COVID-19 paper.
Systematic literature reviews on COVID-19 will also soon be more frequently performed and published. There are many ongoing systematic reviews if we have a look in PROSPERO (International prospective register of systematic reviews):
European Bioinformatics Institute (EMBL-EBI) has launched a COVID-19 Data Portal (with support from EU) to facilitate data sharing and analysis, and to accelerate coronavirus research:
Lastly, the Allen Institute for AI "has partnered with leading research groups to prepare and distribute the COVID-19 Open Research Dataset (CORD-19), a free resource of over 51,000 scholarly articles, including over 40,000 with full text, about COVID-19":
- CORD-19 Explorer – a full-text search for the COVID-19 Open Research Dataset
Search help on COVID-19
If you are a bachelor's or master's student, please make an appointment.
If you're a researcher or a doctoral student, please contact the search consultation group.