The rest of this section is organized as follows: we define the text mining tasks used to categorize and assess the surveyed systems and use these tasks to anchor discussion and comparison of systems described in Table 2. For each task, we (i) summarize features and methodology used by the associated systems and (ii) highlight specific systems that have taken additional steps to tailor their interface for real-world use by biomedical and clinical researchers and practitioners. Such additional steps include joining literature data with biomedical KBs used in clinical settings or adding annotations created by medical experts specifically for COVID-19-related tasks. For each mentioned system, we provide a link to its corresponding row in Table 2.