Search help - COVID-19 Study Register

Search Help

The Cochrane COVID-19 Study Register is "study-based." This means search results contain both study records and reference records. A study can have one or more reference records. Select a study record from the search results to see its reference(s). For more details about the register's design, please see our About page

Basic search

To construct a basic 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



Search filters for dates, study characteristics and PICOs appear on the left-hand page column. When selected, filters will be added to your search query. Select the "x" next filter to remove it. 

Search filters

Date filters

Two date filters are available from the Cochrane COVID-19 Study Register: NEW STUDIES, and UPDATED NEW REFERENCES. 

NEW STUDIES captures only new study records added to the register (i.e., a study that did not previously have a record in the register - for example, a new trial registry record). 

UPDATED NEW REFERENCES captures updated study records and new reference records for existing studies (i.e., a new reference for a study record that was already included in the register - for example, a new journal article for a study that was already included in the register as a preprint or trial registry record).



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

You can also continue searching and then add more results to your export file. This is also a useful way to remove duplicates between two sets of search results.


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). 

Advanced search

To combine additional lines to your search, enter a second search to the search box and select enter/return. This second search will combine with the first search with AND (i.e., will search within the results). Select the "x" next to and of your searches 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. Note: truncation is not supported within a phrase search using quotation marks.

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). Note: nesting terms (brackets) is not supported.  

Complex query



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