In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: To determine the incidence of clinically significant adverse events after long - term , fixed - dose , generic highly active antiretroviral therapy ( HAART ) use among HIV - infected individuals in South India , we examined the experiences of 3154 HIV - infected individuals who received a minimum of 3 months of generic HAART between February 1996 and December 2006 at a tertiary HIV care referral center in South India .
### Output Text:
To determine the incidence of clinically significant adverse events after long - term , fixed - dose , generic highly active antiretroviral therapy ( HAART ) use among HIV - infected individuals in South India , we examined the experiences of 3154 HIV - infected individuals who received a minimum of 3 months of generic HAART between February 1996 and December 2006 at a tertiary HIV care referral center in South India . 