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. 2022 May;27(18):2200322.
doi: 10.2807/1560-7917.ES.2022.27.18.2200322.

COVID-19 vaccine effectiveness against severe disease from SARS-CoV-2 Omicron BA.1 and BA.2 subvariants - surveillance results from southern Sweden, December 2021 to March 2022

Jonas Björk  1   2 , Carl Bonander  3 , Mahnaz Moghaddassi  4 , Magnus Rasmussen  5 , Ulf Malmqvist  2 , Malin Inghammar  5 , Fredrik Kahn  5
Affiliations

COVID-19 vaccine effectiveness against severe disease from SARS-CoV-2 Omicron BA.1 and BA.2 subvariants - surveillance results from southern Sweden, December 2021 to March 2022

Jonas Björk et al. Euro Surveill. 2022 May.

Abstract

We compared vaccine effectiveness against severe COVID-19 between December 2021 and March 2022 when Omicron BA.1 and BA.2 were the dominating SARS-CoV-2 variants in Scania county, Sweden. Effectiveness remained above 80% after the transition from BA.1 to BA.2 among people with at least three vaccine doses but the point estimate decreased markedly to 54% among those with only two doses. Protection from prior infection was also lower after the transition to BA.2. Booster vaccination seems necessary to maintain sufficient protection.

Keywords: SARS-CoV-2 vaccine effectiveness; epidemiological surveillance; variant of concern.

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Conflict of interest statement

Conflict of interest: None declared.

Figures

Figure 1
Figure 1
Surveillance of vaccine effectiveness after at least two doses against severe COVID-19, in Scania, Sweden, March 2021–February 2022 (n = 1,381 cases; n = 13,810 controls)
Figure 2
Figure 2
Vaccine effectiveness against severe COVID-19 in each follow-up period during SARS-CoV-2 Omicron variant dominance, Scania, Sweden, 2021 week 52 – 2022 week 11 (n = 593 cases; n = 5,930 controls)
See this image and copyright information in PMC

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References

    1. Lyngse FP, Kirkeby CT, Denwood M, Christiansen LE, Mølbak K, Møller CH, et al. Transmission of SARS-CoV-2 Omicron VOC subvariants BA.1 and BA.2: Evidence from Danish households. medRxiv. 2022.01.28.22270044. Preprint. 10.1101/2022.01.28.22270044 - DOI
    1. Kirsebom FCM, Andrews N, Stowe J, Toffa S, Sachdeva R, Gallagher E, et al. COVID-19 Vaccine Effectiveness against the Omicron BA.2 variant in England. medRxiv. 2022.03.22.22272691. Preprint. 10.1101/2022.03.22.22272691 - DOI - PMC - PubMed
    1. Altarawneh HN, Chemaitelly H, Ayoub HH, Tang P, Hasan MR, Yassine HM, et al. Effect of prior infection, vaccination, and hybrid immunity against symptomatic BA.1 and BA.2 Omicron infections and severe COVID-19 in Qatar. medRxiv. 2022.03.22.22272745. Preprint. 10.1101/2022.03.22.22272745 - DOI
    1. Björk J, Inghammar M, Moghaddassi M, Rasmussen M, Malmqvist U, Kahn F. High level of protection against COVID-19 after two doses of BNT162b2 vaccine in the working age population - first results from a cohort study in Southern Sweden. Infect Dis (Lond). 2022;54(2):128-33. 10.1080/23744235.2021.1982144 - DOI - PMC - PubMed
    1. Kahn F, Bonander C, Moghaddassi M, Rasmussen M, Malmqvist U, Inghammar M, et al. Risk of severe COVID-19 from the Delta and Omicron variants in relation to vaccination status, sex, age and comorbidities - surveillance results from southern Sweden, July 2021 to January 2022. Euro Surveill. 2022;27(9):2200121. 10.2807/1560-7917.ES.2022.27.9.2200121 - DOI - PMC - PubMed

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