In Japan, clinical information on post COVID-19 syndrome symptoms including nursing care requirements is limited. In this study, we investigated the incidence of acute (within 2 weeks after diagnosis) and post (2-12 weeks after diagnosis) COVID-19 symptoms, as well as nursing care requirements in Japan, when different SARS-CoV2 strains were prevalent and vaccination statuses changed by mass vaccination programs. Electronic health records of 122,045 patients diagnosed with COVID-19 between January 1, 2020, and June 30, 2022, were obtained and divided into three observation periods according to epidemic strains and vaccination coverage. Headache, malaise/fatigue, depression, and disuse syndrome were detected in acute and post COVID-19. The incidence of depression and disuse syndrome in post COVID-19 increased with age. Moreover, increased high-level nursing care requirements after COVID-19 was observed in elderly group. A lower incidence of acute and post COVID-19 symptoms in Japan was linked to increased vaccination coverage of the population and differences in viral strains.