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COVID-19 : Evidence Retrieval Services (CERS): Search Strategy

This guide provides resources and information on the outbreak of coronavirus (COVID-19) for students, researchers and clinicians at the University of Malaya

Search Strategy

CERS employs the use of the following search strategy to search for evidence to answer clinical questions: 

  1. A search is made to ascertain if the question has been appraised previously at the following two databases: CEBM and Singapore Ministry of Health
  2. If the question has not been appraised in these databases, CERS will conduct a comprehensive search using the search strategy described below 

 The search terms used for COVID-19 Evidence Retrieval Service are as follows:

MeSH terms

"coronavirus"[MeSH Terms] OR "coronavirus infections"[MeSH Terms]


“covid-19”, covid 19”, “covid19”, "covid 2019",  “covid”, “2019-novel Corona Virus (2019-nCoV)”, "2019nCoV", "2019 novel CoV", "2019 novel coronavirus*", “2019-nCoV”, “nCoV”, “CoV”, "COV2" “novel cov”, “Novel Coronavirus”, “New Coronavirus”, “Novel Coronavirus Pneumonia (NCP)”, “Coronavirus”, “Corona virus”, coronaviridae, “Severe Acute Respiratory Infection (SARI)”, “Severe Acute Respiratory Syndrome- Corona Virus-2 (SARS-CoV-2)”, "SARS-CoV-19", SARS, SARS2, SARI, NCP, “SARS-CoV-2”, “Wuhan pneumonia”, “Wuhan virus”, “betacoronavir*”, "sarcov2" "wuhan virus*, "severe acute respiratory" pneumonia outbreak" OR “coronavirus infection*", (Wuhan OR Hubei OR Huanan)

The databases used to search for evidence are:

MEDLINE, Cochrane, TRIP Database, Wiley, UpToDate, WHO database, CINAHL, Ovid database- COVID-19 special collection, Scopus, Web of Science, Science Direct, Google Scholar, Google, Guidelines from MoH Malaysia and NICE.

Coronavirus Government Resources


The appraisals are based on the level of evidence. CERS begins at level one of the evidence and then works through to level seven based on the studies available.

Levels of evidence (sometimes called hierarchy of evidence) are assigned to studies based on the methodological quality of their design, validity, and applicability to patient care. These decisions give the "grade (or strength) of recommendation."

Level of Evidence


Level I

Evidence from a systematic review or meta-analysis of all relevant RCTs (randomized controlled trial) or evidence-based clinical practice guidelines based on systematic reviews of RCTs or three or more RCTs of good quality that have similar results.

Level II

Evidence obtained from at least one well-designed RCT

(e.g. large multi-site RCT).

Level III

Evidence obtained from well-designed controlled trials without randomization (e.g. quasi-experimental).

Level IV

Evidence from well-designed case-control or cohort studies.

Level V

Evidence from systematic reviews of descriptive and qualitative studies (meta-synthesis).

Level VI

Evidence from a single descriptive or qualitative study.

Level VII

Evidence from the opinion of authorities and/or reports of expert committees.

This level of effectiveness rating scheme is based on the following: Ackley, B. J., Swan, B. A., Ladwig, G., & Tucker, S. (2008). Evidence-based nursing care guidelines: Medical-surgical interventions. (p. 7). St. Louis, MO: Mosby Elsevier.