Search help - COVID-19 Study Register

Instructions for constructing searches

As the Cochrane COVID-19 Study Register is "study-based," search results contain individual study records with one or more reference. For more details about the register's design, please see our About page

For a simple search

To construct a simple search in Cochrane's COVID-19 Study Register, enter your terms in the search box and select enter/return.

Simple search


Results appear below. Select the "x" next to your search terms to clear your results and begin a new search. 

Clear search


Select filters for study designs or PICOs from the left hand menu. Filters will be added to your search query. 

Search filters


To export results, select your references and then the option "Export" from the bottom of the search results page. 


Export options are RIS (for citation managers - e.g. EndNote, RefWorks) or CSV (for spreadsheet programs - e.g. Excel, Numbers).

Note: RIS files download in RIS format as a text file (.txt.) so the may be opened and viewed in text editors. Import this .txt. file into citation managers just as you would for an .ris. file (i.e. using standard RIS import filters). 

For more advanced searches

To search within results, enter a second term to the search box and select enter/return. Select the "x" next to your search terms to remove from your query. 

Adding a second term


Search operators

Boolean (AND/OR/NOT)

Search with AND to include all of your terms

ventilation AND pneumonia

Search with OR to include any of your terms

ventilation OR CPAP 

Search with NOT to exclude terms

ventilation NOT mechanical

Note: Boolean operators are not case sensitive (use either upper or lower case)

Phrase searching

Use quotation marks to search for exact phrases

"acute respiratory distress syndrome"


Use * to search for alternate endings of terms

prevent* (retrieves prevent, prevents, prevention, etc.) 


Search tips

To build a complex query, combine terms with OR in a single search. Add another search to combine with AND (as below).

Complex query

Note: nesting terms (brackets) is not supported.  

Note: for refining search results using filters, references with contradictory study design information are classified as "unclear." 



Please direct any questions or comments about Cochrane's COVID-19 Study Register to