Characteristics and clinical effectiveness of COVID-19 vaccination in hospitalized patients in Omicron-dominated epidemic wave - a nationwide study in Japan.
Int J Infect Dis
; 132: 84-88, 2023 Jul.
Article
in English
| MEDLINE | ID: covidwho-2304567
ABSTRACT
OBJECTIVES:
COVID-19 was severe in the Delta variant-dominated epidemic wave (fifth wave) in Japan. The clinical characteristics and effectiveness of COVID-19 vaccination are not fully understood in the Omicron variant-dominated wave (sixth and seventh waves), especially in hospitalized patients. We investigated the relationship between vaccination and disease severity in the Omicron-dominated wave and compared these variant-dominated waves.METHODS:
The nationwide COVID-19 database (Japan COVID-19 Task Force) was used to compare clinical characteristics and critical outcomes in patients hospitalized with Delta (fifth, N = 735) vs Omicron-dominated waves (sixth, N = 495; seventh, N = 128).RESULTS:
Patients in the sixth and seventh waves had a lower incidence of critical outcomes and respiratory outcomes, and a higher incidence of bacterial infection, although the mortality rate did not differ significantly between waves. In the sixth and seventh waves, 138 (27.9%) and 29 (22.7%) patients with COVID-19 were unvaccinated, respectively. Multivariable analysis adjusted with previously reported factors revealed that the proportion of (1) critical outcomes and (2) respiratory outcomes decreased in a frequency-dependent manner. Thus, (1) (the number of vaccinations) 1-2 times adjusted odds ratio (aOR) 0.37 (95% confidence interval [CI]; 0.20-0.69); 3-4 times aOR 0.25 (95% CI; 0.11-0.58); and (2) 1-2 times aOR 0.43 (95% CI; 0.27-0.66); 3-4 times aOR 0.36 (95% CI; 0.21-0.60).CONCLUSIONS:
Patients hospitalized with COVID-19 with Omicron infections showed a lower incidence of critical outcomes than those with Delta infections, and COVID-19 vaccination may contribute to preventing respiratory failure.Keywords
Full text:
Available
Collection:
International databases
Database:
MEDLINE
Main subject:
COVID-19
Type of study:
Experimental Studies
/
Observational study
/
Prognostic study
Topics:
Vaccines
/
Variants
Limits:
Humans
Country/Region as subject:
Asia
Language:
English
Journal:
Int J Infect Dis
Journal subject:
Communicable Diseases
Year:
2023
Document Type:
Article
Affiliation country:
J.ijid.2023.04.399
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