SARS-CoV-2 Vaccine Effectiveness against Omicron Variant in Infection-Naive Population, Australia, 2022.
Emerg Infect Dis
; 29(6): 1162-1172, 2023 06.
Article
in English
| MEDLINE | ID: covidwho-2313100
ABSTRACT
SARS-CoV-2 transmission in Western Australia, Australia, was negligible until a wave of Omicron variant infections emerged in February 2022, when >90% of adults had been vaccinated. This unique pandemic enabled assessment of SARS-CoV-2 vaccine effectiveness (VE) without potential interference from background immunity from prior infection. We matched 188,950 persons who had a positive PCR test result during February-May 2022 to negative controls by age, week of test, and other possible confounders. Overall, 3-dose VE was 42.0% against infection and 81.7% against hospitalization or death. A primary series of 2 viral-vectored vaccines followed by an mRNA booster provided significantly longer protection against infection >60 days after vaccination than a 3-dose series of mRNA vaccine. In a population free from non-vaccine-derived background immunity, vaccines against the ancestral spike protein were ≈80% effective for preventing serious outcomes from infection with the SARS-CoV-2 Omicron variant.
Keywords
Full text:
Available
Collection:
International databases
Database:
MEDLINE
Main subject:
Viral Vaccines
/
COVID-19
Type of study:
Experimental Studies
/
Observational study
Topics:
Vaccines
/
Variants
Limits:
Adult
/
Humans
Country/Region as subject:
Oceania
Language:
English
Journal:
Emerg Infect Dis
Journal subject:
Communicable Diseases
Year:
2023
Document Type:
Article
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