Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2023 Mar 31;41(14):2329-2338.
doi: 10.1016/j.vaccine.2023.02.020. Epub 2023 Feb 9.

Assessing COVID-19 vaccine effectiveness against Omicron subvariants: Report from a meeting of the World Health Organization

Daniel R Feikin  1 , Melissa M Higdon  2 , Nick Andrews  3 , Shirley Collie  4 , Maria Deloria Knoll  2 , Jeffrey C Kwong  5 , Ruth Link-Gelles  6 , Tamara Pilishvili  7 , Minal K Patel  8
Affiliations

Assessing COVID-19 vaccine effectiveness against Omicron subvariants: Report from a meeting of the World Health Organization

Daniel R Feikin et al. Vaccine. .

Abstract

Emerging in November 2021, the SARS-CoV-2 Omicron variant of concern exhibited marked immune evasion resulting in reduced vaccine effectiveness against SARS-CoV-2 infection and symptomatic disease. Most vaccine effectiveness data on Omicron are derived from the first Omicron subvariant, BA.1, which caused large waves of infection in many parts of the world within a short period of time. BA.1, however, was replaced by BA.2 within months, and later by BA.4 and BA.5 (BA.4/5). These later Omicron subvariants exhibited additional mutations in the spike protein of the virus, leading to speculation that they might result in even lower vaccine effectiveness. To address this question, the World Health Organization hosted a virtual meeting on December 6, 2022, to review available evidence for vaccine effectiveness against the major Omicron subvariants up to that date. Data were presented from South Africa, the United Kingdom, the United States, and Canada, as well as the results of a review and meta-regression of studies that evaluated the duration of the vaccine effectiveness for multiple Omicron subvariants. Despite heterogeneity of results and wide confidence intervals in some studies, the majority of studies showed vaccine effectiveness tended to be lower against BA.2 and especially against BA.4/5, compared to BA.1, with perhaps faster waning against severe disease caused by BA.4/5 after a booster dose. The interpretation of these results was discussed and both immunological factors (i.e., more immune escape with BA.4/5) and methodological issues (e.g., biases related to differences in the timing of subvariant circulation) were possible explanations for the findings. COVID-19 vaccines still provide some protection against infection and symptomatic disease from all Omicron subvariants for at least several months, with greater and more durable protection against severe disease.

Keywords: Covid-19 vaccines; Omicron variant; Vaccine effectiveness.

PubMed Disclaimer

Conflict of interest statement

Declaration of Competing Interest None

Figures

Fig. 1
Fig. 1
COVID-19 Primary Series Vaccine Effectiveness by Omicron Subvariant.
Fig. 2
Fig. 2
COVID-19 First Booster Dose Vaccine Effectiveness by Omicron Subvariant.
See this image and copyright information in PMC

References

    1. World Health Organization. Classification of Omicron (B.1.1.529): SARS-CoV-2 Variant of Concern. World Health Organization 2021; published online Nov 26. Available from: https://www.who.int/news/item/26-11-2021-classification-of-Omicron-(b.1.... (accessed Dec. 26, 2022).
    1. United Kingdom Health Security Agency. COVID-19 vaccine surveillance report - week 50. United Kingdom Health Security Agency 2021; published online Dec 12. https://assets.publishing.service.gov.uk/government/uploads/system/uploa... (accessed Jan. 23, 2023).
    1. Sheikh A, Kerr S, Woolhouse M, et al. Severity of Omicron variant of concern and vaccine effectiveness against symptomatic disease: national cohort with nested test negative design study in Scotland. University of Edinburgh 2021; published online Dec 22. https://www.research.ed.ac.uk/en/publications/severity-of-Omicron-varian... (preprint) - PMC - PubMed
    1. Hansen CH, Schelde AB, Mousten-Helm IR, et al. Vaccine effectiveness against SARS-CoV-2 infection with the Omicron or Delta variants following a two-dose or booster BNT162b2 or mRNA-1273 vaccination series: A Danish cohort study. medRxiv 2021; published online Dec 23. doi: 10.1101/2021.12.20.21267966. (preprint).
    1. Buchan S.A., Chung H., Brown K.A., et al. Estimated effectiveness of COVID-19 vaccines against Omicron or Delta symptomatic infection and severe outcomes. JAMA Netw Open. 2022 Sep 1;5(9):e2232760. - PMC - PubMed

Publication types

Substances

Supplementary concepts