Perhaps you should try some spelling variations:
vaccine research » medicine research
option research » opinion research, action research, optics research
anti vaccine » ant vaccine, active vaccine, aids vaccine
multi option » multi location, multi population, multi ratios
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: (( anti vaccine research : july 2009 ) OR ( multi option research : july 2009 ))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( anti vaccine research : july 2009 ) OR ( multi option research : july 2009 ))".
• Adding a wildcard symbol may retrieve word variants: (( anti vaccine research : july 2009 ) OR ( multi option research : july 2009 ))*.