Perform simple searches, like the ones you use in Google. A single term for a condition and another for an intervention may suffice.
...vitamin C cold
There is no real need of using a taxonomy, or boolean terms, such as AND or OR (they work, but are rarely needed. If you are really fond of this kind of search strategies, you can use our advanced search).
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OUTCOMES IN PATIENTS TREATED WITH RECOMBINANT HUMAN ACTIVATED PROTEIN C AT AN ACADEMIC MEDICAL CENTER VERSUS THE ENHANCE US TRIAL.: 402