Fear of Infection and Sufficient Vaccine Reservation Information Might Drive Rapid Coronavirus Disease 2019 Vaccination in Japan: Evidence from Twitter Analysis

AbstractBackgroundThe global public health and socioeconomic impacts of coronavirus disease 2019 (COVID-19) have been substantial, making herd immunity by COVID-19 vaccination an important factor for protecting people and retrieving the economy. Among all the countries, Japan became one of the countries with the highest COVID-19 vaccination rate in several months, although the vaccine confidence in Japan is the lowest worldwide.ObjectiveWe attempted to find the reasons for the rapid coronavirus disease 2019 (COVID-19) vaccination in Japan under the lowest vaccine confidence in the world by Twitter analysis.Materials and methodsWe downloaded COVID-19 related Japanese tweets from a large-scale public COVID-19 Twitter chatter dataset within the timeline of February 1, 2021 and September 30, 2021. The daily number of vaccination cases was collected from the official website of the Prime Minister’s Office of Japan. After preprocessing, we applied unigram and bigram token analysis, then calculated the cross correlation and Pearson correlation coefficient (r) between the term frequency and daily vaccination cases. Then we identified vaccine sentiments and emotions of tweets and used the topic modeling to look deeper into the dominant emotions.ResultsWe selected 190,697 vaccine-related tweets after filtering. By n-gram token analysis, we discovered the top unigrams and bigrams over the whole period. In all the combinations of the top six unigrams, tweets with both keywords “reserve” and “venue” showed the largest r = 0.912 (P < 0.001) with the daily vaccination cases. In sentiment analysis, negative sentiment overwhelmed positive sentiment, and fear was the dominant emotion across the period. For the latent Dirichlet allocation model on tweets with fear emotion, the two topics were identified as “infect” and “vaccine confidence”. The expectation of the number of tweets generated from topic “infect” was larger than “vaccine confidence.”ConclusionOur work indicated that awareness of the danger of COVID-19 might increase the willingness to get vaccinated; With sufficient vaccine supply, effective vaccine reservation information delivery may be an important factor for people to get vaccinated; We didn’t find evidence for increased vaccine confidence in Japan during the period in our research. We recommend policymakers to share fair and prompt information about the infectious diseases and vaccination, and make efforts on smoother delivery of vaccine-reservation information.