These data are based on free description from readers’ posts on Japanese hardcopy newspaper articles in the public domain. Upon searching for “coronavirus,” we found 412 reader submissions during the April 7, 2020 to May 25, 2020, 521 during January 8, 2021 to March 21, 2021, 458 during the April 25, 2021 to June 6, 2021, and 519 during July 12, 2021 to September 30, 2021. Topics of content were extracted by Latent Dirichlet Allocation, and then calculating the ratio of topic occurrence in each description.

We conducted document analysis on reader’s posts about newspaper articles in the public domain. Many Japanese newspapers have a section where readers can submit their opinions on any topic. Submissions can be made by mail, fax, or e-mail, and readers are asked to disclose their name, occupation, age, address, and contact information. All or part of these disclosed details are often published in the paper.