Perhaps you should try some spelling variations:
vaccine research » medicine research
multiple actions » multiple actors, multiple options, multiple functions
actions research » action research, actional research, actors research
new vaccine » novel vaccine, anti vaccine
july 2009 » july 2008, july 2007, july 2019

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (( new vaccine research : july 2009 ) or ( multiple actions research : july 2009 ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( new vaccine research : july 2009 ) OR ( multiple actions research : july 2009 )).
• Adding a wildcard symbol may retrieve word variants: (( new vaccine research : july 2009 ) or ( multiple actions research : july 2009 ))*.