Public opinion in Japanese newspaper readers’ posts under the prolonged COVID-19 infection spread 2019–2021: contents analysis using Latent Dirichlet Allocation

During the COVID-19 pandemic, information on what people are interested in and what they are disseminating can be an important public health resource. Most studies on public opinion during the pandemic have focused on social networking services in the context of the early phases of the pandemic or on a short-term basis; research on public opinion outside of social networking services that consider long-term changes has not been conducted. To examine this gap in the research, we analyzed readers’ posts on Japanese hardcopy newspaper articles in the public domain. A total of 1910 such posts published during four emergency declaration periods in Japan were included in the study. Latent Dirichlet Allocation was applied in our analysis to extract topics and Kendall rank correlation coefficients between the emergency declaration periods, and each topic was calculated to examine the effect size. We selected 10 topics and categorized them into three themes: (1) “Life” comprising “Family,” “Daily Life in the COVID-19 Disaster,” “Education in the COVID-19 Disaster,” “The Importance of Humanity,” and “Daily Life unrelated to COVID-19”; (2) “Awareness of the emergency” comprising, “Awareness of being a party to an emergency” and “Concerns about the medical environment,”; and (3) “Policy” comprising “Domestic and foreign policies,” “Opposition to hosting the Tokyo Olympics,” and “Criticisms of the Japanese Government.” This research revealed that, as a result of the exposure to COVID-19-related material over a prolonged period, awareness of the emergency decreased (r = −0.189, p