Figure 11.

Thematic Map. In the thematic map, the horizontal axis represents the centrality, the vertical axis represents the density, and four quadrants were drawn accordingly. The words in the first quadrant (motor themes) indicate that they are essential to TB vaccine research and are well developed, representing the future development trend. The words in the second quadrant (Niche themes) suggest that although they have been well developed, they are not crucial for the current research field. The words in the third quadrant (emerging or themes) indicate that they may be new research fields that have just emerged or past research fields that are about to disappear. Finally, the words in the fourth quadrant (basic themes) indicate that they are essential to TB vaccine research but are not well developed.