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Maeda H, Saito N, Igarashi A, Ishida M, Suami K, Yagiuchi A, Kimura Y, Komino M, Arai H, Morikawa T, Motohashi I, Miyazawa R, Moriyama T, Kamura H, Terada M, Kuwamitsu O, Hayakawa T, Sando E, Ohara Y, Teshigahara O, Suzuki M, Morimoto K. Effectiveness of Messenger RNA Coronavirus Disease 2019 Vaccines Against Symptomatic Severe Acute Respiratory Syndrome Coronavirus 2 Infections During the Delta Variant Epidemic in Japan: Vaccine Effectiveness Real-time Surveillance for SARS-CoV-2 (VERSUS). Clin Infect Dis 2022; 75:1971-1979. [PMID: 35438137 PMCID: PMC9047210 DOI: 10.1093/cid/ciac292] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 04/04/2022] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND Although high vaccine effectiveness of messenger RNA (mRNA) coronavirus disease 2019 (COVID-19) vaccines has been reported in studies in several countries, data are limited from Asian countries, especially against the Delta (B.1.617.2) variant. METHODS We conducted a multicenter test-negative case-control study in patients aged ≥16 years visiting hospitals or clinics with signs or symptoms consistent with COVID-19 from 1 July to 30 September 2021, when the Delta variant was dominant (≥90% of SARS-CoV-2 infections) nationwide in Japan. Vaccine effectiveness of BNT162b2 or mRNA-1273 against symptomatic SARS-CoV-2 infections was evaluated. Waning immunity among patients aged 16-64 years was also assessed. RESULTS We enrolled 1936 patients, including 396 test-positive cases and 1540 test-negative controls for SARS-CoV-2. The median age was 49 years, 53.4% were male, and 34.0% had underlying medical conditions. Full vaccination (receiving 2 doses ≥14 days before symptom onset) was received by 6.6% of cases and 38.8% of controls. Vaccine effectiveness of full vaccination against symptomatic SARS-CoV-2 infections was 88.7% (95% confidence interval [CI], 78.8%-93.9%) among patients aged 16-64 years and 90.3% (95% CI, 73.6%-96.4%) among patients aged ≥65 years. Among patients aged 16-64 years, vaccine effectiveness was 91.8% (95% CI, 80.3%-96.6%) within 1-3 months after full vaccination, and 86.4% (95% CI, 56.9%-95.7%) within 4-6 months. CONCLUSIONS mRNA COVID-19 vaccines had high effectiveness against symptomatic SARS-CoV-2 infections in Japan during July-September 2021, when the Delta variant was dominant nationwide.
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Affiliation(s)
- Haruka Maeda
- Department of Respiratory Infections, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan,Department of Clinical Tropical Medicine, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Nobuo Saito
- Department of Microbiology, Faculty of Medicine, Oita University, Oita, Japan
| | - Ataru Igarashi
- Unit of Public Health and Preventive Medicine, Yokohama City University School of Medicine, Kanagawa, Japan,Department of Health Economics and Outcomes Research, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | | | | | | | - Yuya Kimura
- Saiseikai Kurihashi Hospital, Saitama, Japan
| | | | - Hiromi Arai
- Saiseikai Kurihashi Hospital, Saitama, Japan
| | | | | | - Rei Miyazawa
- Kawasaki Municipal Tama Hospital, Kanagawa, Japan
| | | | | | | | | | | | - Eiichiro Sando
- Kita-Fukushima Medical Center, Fukushima, Japan,Fukushima Medical University, Fukushima, Japan
| | | | | | - Motoi Suzuki
- Infectious Disease Surveillance Center, National Institute of Infectious Diseases, Tokyo, Japan
| | - Konosuke Morimoto
- Correspondence: K. Morimoto, Department of Respiratory Infections, Institute of Tropical Medicine, Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan ()
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