Coronavirus Disease 19 (COVID-19) Vaccine Effectiveness Against Symptomatic Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Infection During Delta-Dominant and Omicron-Dominant Periods in Japan: A Multicenter Prospective Case-control Study (Factors Associated with SARS-CoV-2 Infection and the Effectiveness of COVID-19 Vaccines Study)
Open accessAbstract
Background: Although several coronavirus disease 2019 (COVID-19) vaccines initially showed high efficacy, there have been concerns because of waning immunity and the emergence of variants with immune escape capacity. Methods: A test-negative design case-control study was conducted in 16 healthcare facilities in Japan during the Delta-dominant period (August-September 2021) and the Omicron-dominant period (January-March 2022). Vaccine effectiveness (VE) against symptomatic severe acute respiratory syndrome coronavirus 2 infection was calculated for 2 doses for the Delta-dominant period and 2 or 3 doses for the Omicron-dominant period compared with unvaccinated individuals. Results: The analysis included 5795 individuals with 2595 (44.8%) cases. Among vaccinees, 2242 (55.8%) received BNT162b2 and 1624 (40.4%) received messenger RNA (mRNA)-1273 at manufacturer-recommended intervals. During the Delta-dominant period, VE was 88% (95% confidence interval [CI], 82–93) 14 days to 3 months after dose 2 and 87% (95% CI, 38–97) 3 to 6 months after dose 2. During the Omicron-dominant period, VE was 56% (95% CI, 37–70) 14 days to 3 months since dose 2, 52% (95% CI, 40–62) 3 to 6 months after dose 2, 49% (95% CI, 34–61) 6+ months after dose 2, and 74% (95% CI, 62–83) 14+ days after dose 3. Restricting to individuals at high risk of severe COVID-19 and additional adjustment for preventive measures (ie, mask wearing/high-risk behaviors) yielded similar estimates, respectively. Conclusions: In Japan, where most are infection-naïve, and strict prevention measures are maintained regardless of vaccination status, 2-dose mRNA vaccines provided high protection against symptomatic infection during the Delta-dominant period and moderate protection during the Omicron-dominant period. Among individuals who received an mRNA booster dose, VE recovered to a high level.
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A recent study conducted in Japan reported high-level protection against Omicron infection by an mRNA booster dose (74% at 14 days after the third dose).
“A recent study conducted in Japan80 reported high-level protection against Omicron infection by an mRNA booster dose (74% at 14 days after the third dose), which is consistent with our findings.”
From Protection of the third-dose and fourth-dose mRNA vaccines against SARS-CoV-2 Omicron subvariant: a systematic review and meta-analysis (2023) · cites this paper as [80]
The Results (p. 1) report 74% vaccine effectiveness at 14 or more days after dose 3, and the Discussion (p. 7) describes protection after three doses as high. The estimate is for symptomatic SARS-CoV-2 infection during an Omicron-dominant period, rather than confirmed Omicron infections specifically; it also covers all time from day 14 onward, not only day 14. (LLM, conf=0.82)
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References 27 · Cited by 70
Research works printed but not linked: 21
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- Authors
- Arashiro, T., Arima, Y., Muraoka, H., Sato, A., Oba, K., Uehara, Y., Arioka, H., Yanai, H., Kuramochi, J., Ihara, G., Chubachi, K., Yanagisawa, N., Nagura, Y., Kato, Y., Ueda, A., Numata, A., Kato, H., Ishii, K., Ooki, T., Oka, H., Nishida, Y., Stucky, A., Smith, C., Hibberd, M., Ariyoshi, K., & Suzuki, M.
- Affiliations
- National Institute of Infectious Diseases (JP)
- Clinic for Tamachi , Tokyo , Japan
- KARADA Internal Medicine Clinic , Tokyo , Japan
- Showa General Hospital (JP)
- St. Luke's International Hospital (JP)
- Japan Anti Tuberculosis Association (JP)
- Kuramochi Clinic Interpark , Tochigi , Japan
- Machida Ekimae Naika Clinic , Tokyo , Japan
- Chubachi Internal Respiratory Medicine Clinic , Tokyo , Japan
- Yanagisawa Clinic , Tokyo , Japan
- Shinjuku Home Clinic , Tokyo , Japan
- International University of Health and Welfare Narita Hospital (JP)
- Japanese Red Cross Medical Center (JP)
- Ikebukuro Metropolitan Clinic , Tokyo , Japan
- Yokohama City University Hospital (JP)
- SAITAMA SEKISHINKAI Hospital (JP)
- Social Insurance Saitama Chuo Hospital (JP)
- London School of Hygiene & Tropical Medicine (GB)
- Nagasaki University (JP)
- Corresponding author
- Arashiro, Takeshi
- ORCID
- Venue
- Clinical Infectious Diseases
- Publisher
- Oxford University Press (OUP)
- Published
- 2022-09-01
- Volume
- 76
- Issue
- 3
- Pages
- e108-e115
- ISSN
- 1058-4838 (ISSN-L)
- 1537-6591
- PMC
- PMC9384625
- OpenAlex
- W4289517053
- Cited by
- 70
- References
- 27
- Citations by year
- 2026: 3 · 2025: 15 · 2024: 27 · 2023: 20 · 2022: 5
- FWCI
- 8.18
- Type
- journal article
- Language
- en
- Open access
- hybrid
- doi.org
- Licence
- Locations
- Clinical Infectious Diseases (publishedVersion, cc-by-nc-nd)
- PubMed Central (publishedVersion, cc-by-nc-nd)
- PubMed (publishedVersion)
- LSHTM Research Online (London School of Hygiene and Tropical Medicine) (acceptedVersion)
- Institutional Repositories DataBase (IRDB) (submittedVersion, cc-by-nc-nd)
- Funders
- Japan Agency for Medical Research and Development
- AMED (JP21fk0108612)
- Nagasaki University WISE Programme
- Topics
- Health Sciences › Medicine › Infectious Diseases › SARS-CoV-2 and COVID-19 Research
- Physical Sciences › Mathematics › Modeling and Simulation › COVID-19 epidemiological studies
- Social Sciences › Health › Vaccine Coverage and Hesitancy
- Keywords
- COVID-19 vaccine effectiveness, COVID-19 pandemic, Delta variant, Omicron variant, vaccine waning, BNT162b2, mRNA-1273, third vaccine dose, symptomatic infection, test-negative design, healthcare workers, Japan, COVID-19 prevention measures, masking, high-risk behaviors, immune escape mutations
- MeSH terms
- COVID-19, SARS-CoV-2, COVID-19 Vaccines, Vaccine Efficacy, BNT162 Vaccine, Humans, Japan, RNA, Messenger, Case-Control Studies
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