Effect of vaccination on household transmission of SARS-CoV-2 Delta variant of concern

Frederik Plesner Lyngse*, Kåre Mølbak, Matt Denwood, Lasse Engbo Christiansen, Camilla Holten Møller, Morten Rasmussen, Arieh Sierra Cohen, Marc Stegger, Jannik Fonager, Raphael Niklaus Sieber, Kirsten Maren Ellegaard, Claus Nielsen, Carsten Thure Kirkeby

*Corresponding author af dette arbejde

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Abstract

Effective vaccines protect individuals by not only reducing the susceptibility to infection, but also reducing the infectiousness of breakthrough infections in vaccinated cases. To disentangle the vaccine effectiveness against susceptibility to infection (VES) and vaccine effectiveness against infectiousness (VEI), we took advantage of Danish national data comprising 24,693 households with a primary case of SARS-CoV-2 infection (Delta Variant of Concern, 2021) including 53,584 household contacts. In this setting, we estimated VES as 61% (95%-CI: 59-63), when the primary case was unvaccinated, and VEI as 31% (95%-CI: 26-36), when the household contact was unvaccinated. Furthermore, unvaccinated secondary cases with an infection exhibited a three-fold higher viral load compared to fully vaccinated secondary cases with a breakthrough infection. Our results demonstrate that vaccinations reduce susceptibility to infection as well as infectiousness, which should be considered by policy makers when seeking to understand the public health impact of vaccination against transmission of SARS-CoV-2.

OriginalsprogEngelsk
Artikelnummer3764
TidsskriftNature Communications
Vol/bind13
Udgave nummer1
ISSN2041-1723
DOI
StatusUdgivet - 2022

Bibliografisk note

Funding Information:
We thank Statens Serum Institut and The Danish Health Data Authority for data access. We also thank the rest of the Expert Group for Mathematical Modelling of COVID-19 at Statens Serum Institut for helpful discussions, as well as as the Danish Covid-19 Genome Consortium for typing of positive COVID-19 samples. Frederik Plesner Lyngse gratefully acknowledge funding from: Independent Research Fund Denmark (Grant no. 9061-00035B.); Novo Nordisk Foundation (grant no. NNF17OC0026542); the Danish National Research Foundation through its grant (DNRF-134) to the Center for Economic Behavior and Inequality (CEBI) at the University of Copenhagen.

Funding Information:
We thank Statens Serum Institut and The Danish Health Data Authority for data access. We also thank the rest of the Expert Group for Mathematical Modelling of COVID-19 at Statens Serum Institut for helpful discussions, as well as as the Danish Covid-19 Genome Consortium for typing of positive COVID-19 samples. Frederik Plesner Lyngse gratefully acknowledge funding from: Independent Research Fund Denmark (Grant no. 9061-00035B.); Novo Nordisk Foundation (grant no. NNF17OC0026542); the Danish National Research Foundation through its grant (DNRF-134) to the Center for Economic Behavior and Inequality (CEBI) at the University of Copenhagen.

Publisher Copyright:
© 2022, The Author(s).

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