Vaccine Rollout and Shift in Public Sentiment: Twitter-Based Surveillance Study.

This study aims to find out the variation of Twitter users' sentiment before and after the COVID-19 vaccine rollout. We analyzed all COVID-19 related tweets posted on Twitter within two timeframes: September 2020 (T1) and March 2021 (T2). A total of 3 million tweets from over 132 thousand users were analyzed. We then categorized the users into two groups whose overall sentiment shifted positively or negatively from T1 to T2. Our analysis showed that 27% of users' sentiment shifted from T1 to T2 positively and the users were more confident about vaccine safety and efficacy. Users reported positive sentiments about travelling and the easing of lockdown measures. Also, 20.4% of the users' sentiment shifted negatively from T1 to T2. This group of Twitter users were more concerned about the adverse side effects of the vaccine, the pace of vaccine development as well as the emerging novel coronavirus variants. Interestingly, over half of the users' overall sentiment remained the same in both periods of T1 and T2, indicating indifference about vaccine rollout. We believe that our analysis will support the exploration of public reaction to COVID-19 vaccine rollout and assess policy makers' decision to combat the pandemic.