# 5	18	#4 AND #3 Databases=SCI‐EXPANDED, CPCI‐S Timespan=All Years Lemmatization=On
# 4	1,371,720	Topic=(random* or placebo* or "clinical trial*" or ((singl* or doubl*) NEAR/1 blind*) or allocat* or crossover* or "cross over") OR Title=(trial*) Databases=SCI‐EXPANDED, CPCI‐S Timespan=All Years Lemmatization=On
# 3	117	#2 AND #1 Databases=SCI‐EXPANDED, CPCI‐S Timespan=All Years Lemmatization=On
# 2	5,029	Topic=(hemophilus or haemophilus or "h. influenzae" or nthi) AND Topic=(vaccin* or immuni* or inocul*) Databases=SCI‐EXPANDED, CPCI‐S Timespan=All Years Lemmatization=On
# 1	42,910	Topic=(bronchit* or "chronic obstructive pulmonary disease*" or "chronic obstructive airway* disease*" or "chronic obstructive lung disease*" or coad or copd or aecb) Databases=SCI‐EXPANDED, CPCI‐S Timespan=All Years Lemmatization=On