tetano
Editor, Senior Moderator
J Infect Chemother
. 2025 Oct 22:102840.
doi: 10.1016/j.jiac.2025.102840. Online ahead of print. The continued impact of COVID-19 during the Omicron era on immunocompromised individuals in Japan
Toshibumi Taniguchi[SUP] 1 [/SUP], Mitsuru Hoshino[SUP] 2 [/SUP], Ryotaro Ide[SUP] 3 [/SUP], Tomoyuki Homma[SUP] 4 [/SUP], Keiji Sugiyama[SUP] 5 [/SUP], Shinichi Kanazu[SUP] 6 [/SUP], Atsushi Maruyama[SUP] 7 [/SUP], Kazuhiro Tateda[SUP] 8 [/SUP]
Affiliations
Background: Under Japan's Infectious Disease Act, coronavirus disease-2019 (COVID-19) was reclassified from a category II to a category V infectious disease, changing it from a notifiable disease to a sentinel disease within the surveillance system given the reduced risk of severe outcomes since the Omicron era. However, the COVID-19 disease burden in immunocompromised (IC) individuals during and after the Omicron era has not been sufficiently examined.
Objectives: The COVID-19 disease burden during and after the Omicron era in IC individuals in Japan was investigated.
Methods: This retrospective observational study used an insurance claims database. The baseline period was January 2018-December 2022; the study follow-up period was January 2023-December 2023, which coincided with the Omicron era. Adjusted incidence rate ratios (aIRRs) for COVID-19 related hospitalization, SARS-CoV-2 infection, COVID-19 related intensive care unit (ICU) admission, and COVID-19 related death in IC individuals (vs non-IC individuals) were calculated using Poisson regression models.
Results: Data were analyzed for 3,433,430 individuals, including 179,268 IC individuals. The aIRR (95% confidence interval [CI]) values for hospitalization, SARS-CoV-2 infection, ICU admission, and death were 2.60 (2.47-2.74), 1.12 (1.09-1.15), 2.94 (2.54-3.39), and 3.34 (3.07-3.65), respectively. Among IC individuals who had B cell-depleting therapy, solid organ transplantation, and hematological malignancies, the aIRR (95% CI) values for hospitalization were 5.10 (4.19-6.22), 4.00 (0.56-28.40), and 3.03 (2.65-3.45), respectively.
Conclusion: IC individuals had a high COVID-19 disease burden during the Omicron era. Appropriate preventive measures should be continued for this population.
Keywords: COVID-19; Omicron; disease burden; immunocompromised individuals; insurance claims data.
. 2025 Oct 22:102840.
doi: 10.1016/j.jiac.2025.102840. Online ahead of print. The continued impact of COVID-19 during the Omicron era on immunocompromised individuals in Japan
Toshibumi Taniguchi[SUP] 1 [/SUP], Mitsuru Hoshino[SUP] 2 [/SUP], Ryotaro Ide[SUP] 3 [/SUP], Tomoyuki Homma[SUP] 4 [/SUP], Keiji Sugiyama[SUP] 5 [/SUP], Shinichi Kanazu[SUP] 6 [/SUP], Atsushi Maruyama[SUP] 7 [/SUP], Kazuhiro Tateda[SUP] 8 [/SUP]
Affiliations
- PMID: 41135830
- DOI: 10.1016/j.jiac.2025.102840
Background: Under Japan's Infectious Disease Act, coronavirus disease-2019 (COVID-19) was reclassified from a category II to a category V infectious disease, changing it from a notifiable disease to a sentinel disease within the surveillance system given the reduced risk of severe outcomes since the Omicron era. However, the COVID-19 disease burden in immunocompromised (IC) individuals during and after the Omicron era has not been sufficiently examined.
Objectives: The COVID-19 disease burden during and after the Omicron era in IC individuals in Japan was investigated.
Methods: This retrospective observational study used an insurance claims database. The baseline period was January 2018-December 2022; the study follow-up period was January 2023-December 2023, which coincided with the Omicron era. Adjusted incidence rate ratios (aIRRs) for COVID-19 related hospitalization, SARS-CoV-2 infection, COVID-19 related intensive care unit (ICU) admission, and COVID-19 related death in IC individuals (vs non-IC individuals) were calculated using Poisson regression models.
Results: Data were analyzed for 3,433,430 individuals, including 179,268 IC individuals. The aIRR (95% confidence interval [CI]) values for hospitalization, SARS-CoV-2 infection, ICU admission, and death were 2.60 (2.47-2.74), 1.12 (1.09-1.15), 2.94 (2.54-3.39), and 3.34 (3.07-3.65), respectively. Among IC individuals who had B cell-depleting therapy, solid organ transplantation, and hematological malignancies, the aIRR (95% CI) values for hospitalization were 5.10 (4.19-6.22), 4.00 (0.56-28.40), and 3.03 (2.65-3.45), respectively.
Conclusion: IC individuals had a high COVID-19 disease burden during the Omicron era. Appropriate preventive measures should be continued for this population.
Keywords: COVID-19; Omicron; disease burden; immunocompromised individuals; insurance claims data.