Outcomes of COVID-19 in the Omicron-predominant wave: large-scale real-world data analysis with a comparison to influenza
Abstract Purpose Studies on COVID-19 mortality during the Omicron-predominant wave have focused primarily on the inpatient/emergency room setting, and real-world data including both inpatients and outpatients are lacking. Methods Patients diagnosed with COVID-19 (n = 27,440,148) or influenza (n = 8,...
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| Format: | Article |
| Language: | English |
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BMC
2025-02-01
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| Series: | Pneumonia |
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| Online Access: | https://doi.org/10.1186/s41479-025-00158-y |
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| author | Koichi Miyashita Hironao Hozumi Kazuki Furuhashi Eiji Nakatani Yusuke Inoue Hideki Yasui Yuzo Suzuki Masato Karayama Noriyuki Enomoto Tomoyuki Fujisawa Naoki Inui Toshiyuki Ojima Takafumi Suda |
| author_facet | Koichi Miyashita Hironao Hozumi Kazuki Furuhashi Eiji Nakatani Yusuke Inoue Hideki Yasui Yuzo Suzuki Masato Karayama Noriyuki Enomoto Tomoyuki Fujisawa Naoki Inui Toshiyuki Ojima Takafumi Suda |
| author_sort | Koichi Miyashita |
| collection | DOAJ |
| description | Abstract Purpose Studies on COVID-19 mortality during the Omicron-predominant wave have focused primarily on the inpatient/emergency room setting, and real-world data including both inpatients and outpatients are lacking. Methods Patients diagnosed with COVID-19 (n = 27,440,148) or influenza (n = 8,179,641) from January 2020 to April 2023 were identified using nationwide claims data in Japan. Patients with COVID-19 in the Omicron-predominant wave were compared with their counterparts in earlier waves, and a subset of the former group (May 2022–April 2023) was compared with patients with influenza as controls. Results The mortality rates (average number of deaths/cases per week) of COVID-19 decreased over time, being 2.7% (169/6312), 2.1% (397/18,754), 0.7% (195/28,273), and 0.4% (1613/378,848) in the wild-type–, Alpha-, Delta-, and Omicron-predominant waves, respectively. However, the number of deaths increased substantially in the Omicron-predominant wave, especially among the elderly (e.g., in the Delta- and Omicron-predominant waves, the average numbers of deaths/cases per week were < 1/5527 (< 0.01%) and 4/105,763 (< 0.01%) respectively, in patients aged 0–19, versus 101/925 (10.9%) and 1212/20,771 (5.8%), respectively, in patients aged ≥ 80). The mortality rate was lower for patients with COVID-19 than in those with influenza among those aged ≤ 39 years but higher among those aged ≥ 40 years. Conclusions In the Omicron-predominant wave, the mortality rate of COVID-19 decreased, but the number of patients increased, leading to a substantial increase in the number of deaths, especially among the elderly. The mortality rate of COVID-19 was higher than that of influenza in the elderly but not in the young, highlighting the need for age-specific interventions. |
| format | Article |
| id | doaj-art-44e80bf3fb7643cb9ef4db874b8e412a |
| institution | Kabale University |
| issn | 2200-6133 |
| language | English |
| publishDate | 2025-02-01 |
| publisher | BMC |
| record_format | Article |
| series | Pneumonia |
| spelling | doaj-art-44e80bf3fb7643cb9ef4db874b8e412a2025-02-09T12:40:31ZengBMCPneumonia2200-61332025-02-0117111210.1186/s41479-025-00158-yOutcomes of COVID-19 in the Omicron-predominant wave: large-scale real-world data analysis with a comparison to influenzaKoichi Miyashita0Hironao Hozumi1Kazuki Furuhashi2Eiji Nakatani3Yusuke Inoue4Hideki Yasui5Yuzo Suzuki6Masato Karayama7Noriyuki Enomoto8Tomoyuki Fujisawa9Naoki Inui10Toshiyuki Ojima11Takafumi Suda12Second Division, Department of Internal Medicine, Hamamatsu University School of MedicineSecond Division, Department of Internal Medicine, Hamamatsu University School of MedicineSecond Division, Department of Internal Medicine, Hamamatsu University School of MedicineDepartment of Biostatistics and Data Science, Graduate School of Medical Science, Nagoya City UniversitySecond Division, Department of Internal Medicine, Hamamatsu University School of MedicineSecond Division, Department of Internal Medicine, Hamamatsu University School of MedicineSecond Division, Department of Internal Medicine, Hamamatsu University School of MedicineSecond Division, Department of Internal Medicine, Hamamatsu University School of MedicineSecond Division, Department of Internal Medicine, Hamamatsu University School of MedicineSecond Division, Department of Internal Medicine, Hamamatsu University School of MedicineDepartment of Clinical Pharmacology and Therapeutics, Hamamatsu University School of MedicineDepartment of Community Health and Preventive Medicine, Hamamatsu University School of MedicineSecond Division, Department of Internal Medicine, Hamamatsu University School of MedicineAbstract Purpose Studies on COVID-19 mortality during the Omicron-predominant wave have focused primarily on the inpatient/emergency room setting, and real-world data including both inpatients and outpatients are lacking. Methods Patients diagnosed with COVID-19 (n = 27,440,148) or influenza (n = 8,179,641) from January 2020 to April 2023 were identified using nationwide claims data in Japan. Patients with COVID-19 in the Omicron-predominant wave were compared with their counterparts in earlier waves, and a subset of the former group (May 2022–April 2023) was compared with patients with influenza as controls. Results The mortality rates (average number of deaths/cases per week) of COVID-19 decreased over time, being 2.7% (169/6312), 2.1% (397/18,754), 0.7% (195/28,273), and 0.4% (1613/378,848) in the wild-type–, Alpha-, Delta-, and Omicron-predominant waves, respectively. However, the number of deaths increased substantially in the Omicron-predominant wave, especially among the elderly (e.g., in the Delta- and Omicron-predominant waves, the average numbers of deaths/cases per week were < 1/5527 (< 0.01%) and 4/105,763 (< 0.01%) respectively, in patients aged 0–19, versus 101/925 (10.9%) and 1212/20,771 (5.8%), respectively, in patients aged ≥ 80). The mortality rate was lower for patients with COVID-19 than in those with influenza among those aged ≤ 39 years but higher among those aged ≥ 40 years. Conclusions In the Omicron-predominant wave, the mortality rate of COVID-19 decreased, but the number of patients increased, leading to a substantial increase in the number of deaths, especially among the elderly. The mortality rate of COVID-19 was higher than that of influenza in the elderly but not in the young, highlighting the need for age-specific interventions.https://doi.org/10.1186/s41479-025-00158-yCOVID-19InfluenzaMortalityNational Database of Health Insurance Claims and Specific Health Checkups of JapanNDB |
| spellingShingle | Koichi Miyashita Hironao Hozumi Kazuki Furuhashi Eiji Nakatani Yusuke Inoue Hideki Yasui Yuzo Suzuki Masato Karayama Noriyuki Enomoto Tomoyuki Fujisawa Naoki Inui Toshiyuki Ojima Takafumi Suda Outcomes of COVID-19 in the Omicron-predominant wave: large-scale real-world data analysis with a comparison to influenza Pneumonia COVID-19 Influenza Mortality National Database of Health Insurance Claims and Specific Health Checkups of Japan NDB |
| title | Outcomes of COVID-19 in the Omicron-predominant wave: large-scale real-world data analysis with a comparison to influenza |
| title_full | Outcomes of COVID-19 in the Omicron-predominant wave: large-scale real-world data analysis with a comparison to influenza |
| title_fullStr | Outcomes of COVID-19 in the Omicron-predominant wave: large-scale real-world data analysis with a comparison to influenza |
| title_full_unstemmed | Outcomes of COVID-19 in the Omicron-predominant wave: large-scale real-world data analysis with a comparison to influenza |
| title_short | Outcomes of COVID-19 in the Omicron-predominant wave: large-scale real-world data analysis with a comparison to influenza |
| title_sort | outcomes of covid 19 in the omicron predominant wave large scale real world data analysis with a comparison to influenza |
| topic | COVID-19 Influenza Mortality National Database of Health Insurance Claims and Specific Health Checkups of Japan NDB |
| url | https://doi.org/10.1186/s41479-025-00158-y |
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