tetano
Editor, Senior Moderator
Emerg Infect Dis
. 2023 May 4;29(6).
doi: 10.3201/eid2906.230130. Online ahead of print.
SARS-CoV-2 Vaccine Effectiveness against Omicron Variant in Infection-Naive Population, Australia, 2022
Lauren E Bloomfield, Sera Ngeh, Gemma Cadby, Kate Hutcheon, Paul V Effler
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: 2019 novel coronavirus disease; Australia; COVID-19; Omicron; SARS-CoV-2; SARS-CoV-2–naive; coronavirus disease; respiratory infections; severe acute respiratory syndrome coronavirus 2; vaccine effectiveness; viruses; zoonoses.
. 2023 May 4;29(6).
doi: 10.3201/eid2906.230130. Online ahead of print.
SARS-CoV-2 Vaccine Effectiveness against Omicron Variant in Infection-Naive Population, Australia, 2022
Lauren E Bloomfield, Sera Ngeh, Gemma Cadby, Kate Hutcheon, Paul V Effler
- PMID: 37141626
- DOI: 10.3201/eid2906.230130
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: 2019 novel coronavirus disease; Australia; COVID-19; Omicron; SARS-CoV-2; SARS-CoV-2–naive; coronavirus disease; respiratory infections; severe acute respiratory syndrome coronavirus 2; vaccine effectiveness; viruses; zoonoses.