Differences in patient characteristics, treatments, and mortality of COVID-19 between 2022 and 2020-2021.

In 2021, vaccines against SARS-CoV-2 were developed, and the Omicron variant emerged. This study compared the characteristics, treatments, and mortality of patients with coronavirus disease 2019 (COVID-19) between 2022 and 2020-2021, using administrative claims data linked with vaccine records in a Japanese city. We identified patients underwent COVID-19 antigen or polymerase chain reaction tests and were diagnosed with COVID-19. Patient characteristics, treatments, and mortality were compared between 2022 and 2020-2021 among those diagnosed with COVID-19 and those who died. We identified 26,262 patients with COVID-19. The mortality in 2022 was lower than that in 2020-2021 (0.6% vs. 1.7%; P<0.01). Patients in 2022 were significantly less likely to receive oxygen therapy, high-flow nasal oxygenation, mechanical ventilation, steroid, or tocilizumab than those in 2020-2021. Among the deceased, the proportion of those aged ≥65 years was significantly higher in 2022 than in 2020-2021 (98.4% vs. 88.6%). On logistic regression, older age, male, and ≥3 comorbidities were associated with higher mortality, whereas ≥3 vaccinations were associated with lower mortality. Patients with COVID-19 in 2022 were less likely to require respiratory care or succumb to the disease. Older patients were more likely to die in 2022 than in 2020-2021.