Effectiveness of the XBB.1.5 updated COVID-19 vaccine against hospitalisation: a nation-wide cohort study in Denmark, October 2023

3 Pages Posted: 22 Nov 2023

See all articles by Christian Holm Hansen

Christian Holm Hansen

Statens Serum Institut - Infectious Disease Epidemiology & Prevention

Ida Rask Moustsen-Helms

Statens Serum Institut

Morten Rasmussen

Statens Serum Institut - Virus Research & Development Laboratory

Bolette Søborg

Statens Serum Institut - Infectious Disease Epidemiology & Prevention

Palle Valentiner-Branth

Statens Serum Institut - Infectious Disease Epidemiology & Prevention

Henrik Ullum

Statens Serum Institut

Date Written: November 8, 2023

Abstract

The XBB.1.5 updated COVID-19 mRNA vaccines currently form part of the national immunisation programmes in many countries including Denmark. Here we present a cohort analysis with national electronic health registry data estimating the protection offered by the updated vaccines against hospital admission in October 2023. After adjustment in a Cox proportional hazards regression model for sex, age, residency region and comorbidities, those who had received the seasonal COVID-19 vaccine were much less likely to have been hospitalised for COVID-19 compared with those who had not received the vaccine (HR=0.247, 95% CI 0.157, 0.389), although a negative control outcome analysis indicated that the unvaccinated group had somewhat poorer health in general. Overall, our early results indicate a high level of protection from the XBB.1.5 vaccines.

Note:

Funding Information: There was no separate funding source for this study. All authors are employed by Statens Serum Institut, Copenhagen, Denmark.

Conflict of Interests: The authors have no competing interest to declare.

Keywords: Vaccine effectiveness, SARS-CoV-2, COVID-19, negative control outcome, cohort analysis

Suggested Citation

Hansen, Christian Holm and Moustsen-Helms, Ida Rask and Rasmussen, Morten and Søborg, Bolette and Valentiner-Branth, Palle and Ullum, Henrik, Effectiveness of the XBB.1.5 updated COVID-19 vaccine against hospitalisation: a nation-wide cohort study in Denmark, October 2023 (November 8, 2023). Available at SSRN: https://ssrn.com/abstract=4627268 or http://dx.doi.org/10.2139/ssrn.4627268

Christian Holm Hansen (Contact Author)

Statens Serum Institut - Infectious Disease Epidemiology & Prevention

Ida Rask Moustsen-Helms

Statens Serum Institut

Morten Rasmussen

Statens Serum Institut - Virus Research & Development Laboratory ( email )

Copenhagen
Denmark

Bolette Søborg

Statens Serum Institut - Infectious Disease Epidemiology & Prevention ( email )

Copenhagen
Denmark

Palle Valentiner-Branth

Statens Serum Institut - Infectious Disease Epidemiology & Prevention

Henrik Ullum

Statens Serum Institut ( email )

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