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. 2021 Sep 15;39(39):5456-5460.
doi: 10.1016/j.vaccine.2021.08.060. Epub 2021 Aug 19.

Vaccine effectiveness against infection and onwards transmission of COVID-19: Analysis of Belgian contact tracing data, January-June 2021

Toon Braeye  1 , Laura Cornelissen  1 , Lucy Catteau  1 , Freek Haarhuis  1 , Kristiaan Proesmans  1 , Karin De Ridder  1 , Achille Djiena  2 , Romain Mahieu  3 , Frances De Leeuw  3 , Alex Dreuw  4 , Naima Hammami  5 , Sophie Quoilin  1 , Herman Van Oyen  1 , Chloé Wyndham-Thomas  1 , Dieter Van Cauteren  1
Affiliations

Vaccine effectiveness against infection and onwards transmission of COVID-19: Analysis of Belgian contact tracing data, January-June 2021

Toon Braeye et al. Vaccine. .

Abstract

In Belgium, high-risk contacts of an infected person were offered PCR-testing irrespective of their vaccination status. We estimated vaccine effectiveness (VE) against infection and onwards transmission, controlling for previous infections, household-exposure and temporal trends. We included 301,741 tests from 25 January to 24 June 2021. Full-schedule vaccination was associated with significant protection against infection. In addition, mRNA-vaccines reduced onward transmission: VE-estimates increased to >90% when index and contact were fully vaccinated. The small number of viral-vector vaccines included limited interpretability.

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Conflict of interest statement

Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Figures

Fig. 1
Fig. 1
Vaccine Effectiveness-estimates (VE) and 95% credibility intervals against infection by vaccination status (upper) or by previous infection (lower) of the contact after high-risk contact (HRC) with an unvaccinated index (SD = single dose, RR = relative risk).
Fig. 2
Fig. 2
Vaccine Effectiveness-estimates (VE) and 95% credibility intervals against onward transmission by vaccination status (upper) or by previous infection (lower) of the index after high-risk contact with an unvaccinated contact (SD = single dose, RR= relative risk).
Fig. 3
Fig. 3
Vaccine Effectiveness-estimates (VE) and 95% credibility intervals by vaccination status of index and high-risk contact (HRC). The background color represents the VE-estimate. Combinations in which both the index case and high-risk contact were partially vaccinated are in the grey box. Combinations in which both the index case and high-risk contact were fully vaccinated are in the black box (SD = single dose).
See this image and copyright information in PMC

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