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: The objectives were to assess the efficacy of lamivudine in reducing the incidence of HBV reactivation , and diminishing morbidity and mortality during CT .
### Output Text:
The objectives were to assess the efficacy of <span class="chemical">lamivudine</span> in reducing the incidence of HBV reactivation , and diminishing morbidity and mortality during CT . 