Online social networks (OSNs) are today a primary way to spread and consume information. Maybe the most important aspect of OSNs, both an opportunity and a weakness, is that OSNs are open: users can post anything, which leads to proliferation of information with various degrees of truthfulness. This impacts the volume of information, trending topics, and sentiment of users vis-a-vis of these topics. Our goal in this work is to analyze the spreading of information in Twitter, volume-wise and sentiment-wise (positive or negative), for COVID-19 vaccines overall, and for some specific brands. Our analysis was carried on over five 10-day time-windows in 2021, starting from February and until October. We also looked at what were the most popular tweets we collected during our predefined time-windows, and, by looking at the retweets counts, we observed how they trended over time.