2.3.1. Outcome Variables

The outcome index used in this study was the SARS-CoV-2 diagnosis status. If an individual chose the answer, "I have been diagnosed as SARS-CoV-2 infection at a medical facility and am currently under treatment" or "I was diagnosed as SARS-CoV-2 infection at a medical facility and have already recovered", then he/she was categorized into a SARS-CoV-2 group and the presence of diagnosis was used as the primary outcome variable.

This study established that the subjects "experienced SARS-CoV-2 infection" only if they were diagnosed with it at a medical facility.

The questionnaire was conducted 3 times: in October 2020, January 2021, and May 2021. If there was a discrepancy between the answer about SARS-CoV-2 diagnosis (e.g., a participant answered,"I was diagnosed as SARS-CoV-2 infection" in the first questionnaire and "Not diagnosed" in the second one), the data were omitted.
