Reduction in COVID-19 Vaccine Effectiveness against SARS-CoV-2 Variants in Seoul according to Age, Sex, and Symptoms: A Test-Negative Case-Control Study.
Int J Environ Res Public Health
; 19(24)2022 12 16.
Article
in English
| MEDLINE | ID: covidwho-2163403
ABSTRACT
BACKGROUND:
We evaluated vaccine effectiveness (VE) against infections with SARS-CoV-2 variants of concern in Seoul, the capital of the Republic of Korea, having the highest population density in the country, under real-world conditions.METHODS:
We evaluated the reduction in the effectiveness of mRNA and viral-vector COVID-19 vaccines against infection by the SARS-CoV-2 delta variant in a subpopulation from April 2021 to July 2021 who visited screening clinics in Seoul using a test-negative case-control study design. Moreover, we conducted a case-control study matching the ten-year-old age group, sex, healthcare workers, and five districts of Seoul, which are considered confounding factors.RESULTS:
The full VE in the pre-delta-dominant period was 95.0% (95% confidence interval [CI] 91.2-97.2); however, it decreased to 61.1% (95% CI 53.2-67.6) during the delta-dominant period. Notably, we found that COVID-19 VE was significantly decreased in individuals aged ≥80 years (52.9%, 95% CI -9.9-79.8), men (50.6 %, 95% CI 39.4-59.8), and asymptomatic individuals (49.8%, 95% CI 36.5-60.3) during the widespread SARS-CoV-2 delta variant circulation.CONCLUSIONS:
Vaccine-mediated protection drastically declined during the delta-dominant period and in vulnerable groups. This study suggests the requirement for additional countermeasures, such as the administration of a booster vaccine, in vulnerable groups based on age, sex, and symptomatic manifestation.Keywords
Full text:
Available
Collection:
International databases
Database:
MEDLINE
Main subject:
COVID-19 Vaccines
/
COVID-19
Type of study:
Experimental Studies
/
Observational study
/
Randomized controlled trials
Topics:
Vaccines
/
Variants
Limits:
Child
/
Humans
/
Male
Country/Region as subject:
Asia
Language:
English
Year:
2022
Document Type:
Article
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