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Vaccine Effectiveness Against COVID19-Infection and Onward Transmission by Variant of Concern and Time Since Vaccination, Belgian Contact Tracing, 2021

28 Pages Posted: 4 Jan 2022

See all articles by Toon Braeye

Toon Braeye

Sciensano

Lucy Catteau

Sciensano

Ruben Brondeel

Sciensano

Joris van Loenhout

Sciensano

Kristiaan Proesmans

Sciensano

Laura Cornelissen

Scientific directorate of Epidemiology and Public Health - Service of Epidemiology of Infectious Diseases

Herman Van Oyen

Sciensano

Veerle Stouten

Sciensano

Pierre Hubin

Sciensano

Matthieu Billuart

Sciensano

Achille Djiena

affiliation not provided to SSRN

Romain Mahieu

affiliation not provided to SSRN

Naima Hammami

affiliation not provided to SSRN

Dieter Van Cauteren

Sciensano

Chloé Wyndham-Thomas

Sciensano

More...

Abstract

Background: During the first half of 2021, we observed high vaccine effectiveness (VE) against SARS-CoV2-infection. The replacement of the alpha-‘variant of concern’ (VOC) by the delta-VOC and uncertainty about the time course of immunity called-for a re-assessment. 

Methods: We estimated VE against transmission of infection (VET) from Belgian contact tracing data for high-risk contacts between 26/01/2021 and 30/11/2021 by two components: susceptibility of the contact (VEs) and infectiousness of breakthrough cases (VEi) for a complete schedule of Ad26.COV2.S, ChAdOx1, BNT162b2, mRNA-1273 as well as infection-acquired and hybrid immunity. We adjusted for personal characteristics (age, sex, household), background exposure and duration of exposure. 

Findings: VET-estimates were higher for mRNA-vaccines, over 90%, compared to viral vector vaccines: 63% and 78% for Ad26COV2.S and ChAdOx1 respectively (alpha-VOC, 0-50 days after vaccination). Waning rates were comparable across vaccine brands, with a 50% VEs-reduction in 198 (95%CI 181-224) days and a 50% VEi-reduction in 175 (95%CI 145-248) days. We observed faster waning of VEi in the age group 65-84 years. The delta-VOC was associated with a 40% increase in odds of transmission and a decrease of VEs (69 to 56%) and especially of VEi (73 to 45% for BNT162b2). Infection-acquired and hybrid immunity were less affected by the delta-VOC and waned slower than vaccine-induced immunity. 

Interpretation: VET-estimates, while remaining significant, were reduced by the delta-VOC and waned over time. We observed faster waning in males and the age group 65-84 years. We should seek to improve vaccine-induced protection in these persons, especially when vaccinated with viral-vector vaccines.

Funding Information: This study was supported by the Belgian Federal and Regional Authorities through funding for the LINK-VACC project and organizing and financing of contact tracing.

Declaration of Interests: No conflicts of interest.

Ethics Approval Statement: Data linkage and collection within the data-warehouse has been approved by the information security committee.

Keywords: vaccine effectiveness, Transmission, SARS-CoV2, infection, contact tracing, susceptibility, infectiousness, Bayesian analysis, Covid19

Suggested Citation

Braeye, Toon and Catteau, Lucy and Brondeel, Ruben and van Loenhout, Joris and Proesmans, Kristiaan and Cornelissen, Laura and Van Oyen, Herman and Stouten, Veerle and Hubin, Pierre and Billuart, Matthieu and Djiena, Achille and Mahieu, Romain and Hammami, Naima and Van Cauteren, Dieter and Wyndham-Thomas, Chloé, Vaccine Effectiveness Against COVID19-Infection and Onward Transmission by Variant of Concern and Time Since Vaccination, Belgian Contact Tracing, 2021. Available at SSRN: https://ssrn.com/abstract=4000559 or http://dx.doi.org/10.2139/ssrn.4000559

Lucy Catteau

Sciensano ( email )

Rue Juliette Wytsmanstraat 14
Brussels, 1050
Belgium

Ruben Brondeel

Sciensano ( email )

Rue Juliette Wytsmanstraat 14
Brussels, 1050
Belgium

Joris Van Loenhout

Sciensano ( email )

Rue Juliette Wytsmanstraat 14
Brussels, 1050
Belgium

Kristiaan Proesmans

Sciensano ( email )

Rue Juliette Wytsmanstraat 14
Brussels, 1050
Belgium

Laura Cornelissen

Scientific directorate of Epidemiology and Public Health - Service of Epidemiology of Infectious Diseases ( email )

Belgium

Herman Van Oyen

Sciensano ( email )

Rue Juliette Wytsmanstraat 14
Brussels, 1050
Belgium

Veerle Stouten

Sciensano ( email )

Rue Juliette Wytsmanstraat 14
Brussels, 1050
Belgium

Pierre Hubin

Sciensano ( email )

Rue Juliette Wytsmanstraat 14
Brussels, 1050
Belgium

Matthieu Billuart

Sciensano ( email )

Rue Juliette Wytsmanstraat 14
Brussels, 1050
Belgium

Achille Djiena

affiliation not provided to SSRN ( email )

No Address Available

Romain Mahieu

affiliation not provided to SSRN ( email )

No Address Available

Naima Hammami

affiliation not provided to SSRN ( email )

No Address Available

Dieter Van Cauteren

Sciensano ( email )

Rue Juliette Wytsmanstraat 14
Brussels, 1050
Belgium

Chloé Wyndham-Thomas

Sciensano ( email )

Rue Juliette Wytsmanstraat 14
Brussels, 1050
Belgium