Before revision:  The text analysisshows that the researchers are more concerned about understanding symptoms and developing vaccination; news and politicians are mainly discussing about traveland hygiene; and URLanizations focuses on hygiene. Our descriptive analysis helps us to extract various features that we used to classify tweets among the four clusters with an accuracy of 96\% AUC ROC.
After revision:  According to the text analysis, the (i) research cluster is more concerned with recognizing symptoms and the development of vaccination; (ii) news and politics clusters are mostly concerned with travel. We then show that we can use our findings to classify tweets among the four clusters with an accuracy of 96\% AUC ROC.