19205
Three studies showed statistically significant reductions in the number of individuals with emergent HIV - 1 infection when FTC / TDF was compared with placebo over the =~ 1 - to 2 - year study periods .
 Chemical: FTC; Chemical: TDF
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
 Entities: FTC, TDF 
Answer:
 Chemical: FTC; Chemical: TDF