Effectiveness of mRNA Booster Vaccination Against Mild, Moderate, and Severe COVID-19 Caused by the Omicron Variant in a Large, Population-Based, Norwegian Cohort.
J Infect Dis
; 226(11): 1924-1933, 2022 Nov 28.
Article
in English
| MEDLINE | ID: covidwho-2077787
ABSTRACT
BACKGROUND:
Understanding how booster vaccination can prevent moderate and severe illness without hospitalization is crucial to evaluate the full advantage of mRNA boosters.METHODS:
We followed 85 801 participants (aged 31-81 years) in 2 large population-based cohorts during the Omicron BA.1/2 wave. Information on home testing, PCR testing, and symptoms of coronavirus disease 2019 (COVID-19) was extracted from biweekly questionnaires covering the period 12 January 2022 to 7 April 2022. Vaccination status and data on previous SARS-CoV-2 infection were obtained from national registries. Cox regression was used to estimate the effectiveness of booster vaccination compared to receipt of 2-dose primary series >130 days previously.RESULTS:
The effectiveness of booster vaccination increased with increasing severity of COVID-19 and decreased with time since booster vaccination. The effectiveness against severe COVID-19 was reduced from 80.9% shortly after booster vaccination to 63.4% in the period >90 days after vaccination. There was hardly any effect against mild COVID-19. The effectiveness tended to be lower among subjects aged ≥60 years than those aged <50 years.CONCLUSIONS:
This is the first population-based study to evaluate booster effectiveness against self-reported mild, moderate, and severe COVID-19. Our findings contribute valuable information on duration of protection and thus timing of additional booster vaccinations.Keywords
Full text:
Available
Collection:
International databases
Database:
MEDLINE
Main subject:
COVID-19
Type of study:
Cohort study
/
Experimental Studies
/
Observational study
/
Prognostic study
Topics:
Vaccines
/
Variants
Limits:
Humans
Language:
English
Journal:
J Infect Dis
Year:
2022
Document Type:
Article
Affiliation country:
Infdis
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