Vaccines

5C-03 - Evaluating the Safety Profile of the Janssen COVID-19 Vaccine (JCOVDEN): A VAC4EU post-authorization safety study

Tuesday, August 26, 2025

9:00 AM - 9:15 AM ET

Co-Author(s)

FA

Fariba Ahmadizar, PharmD, PhD

Data science and biostatistics department, Julius Global Health, University Medical Center Utrecht, Utrecht, The Netherlands, Netherlands
AC

Albert Cid Royo

Department of Data Science and Biostatistics, Julius Center for Health Science and Primary Care, University Medical Center of Utrecht, Utrecht University, Utrecht, The Netherlands, Netherlands
OR

Oisin Ryan

Assistant Professor, University Medical Center Utrecht, Utrecht, the Netherlands, Netherlands
Estel Plana, MSc

Director Biostatistician
Pharmacoepidemiology and Risk Management, RTI Health Solutions, Barcelona, Spain, Spain
JR

Judit Riera Arnau, MD

UMC utrecht, Spain
AD

Amirreza Dehgahn Tarazjani

Department of Data Science and Biostatistics, Julius Center for Health Science and Primary Care, University Medical Center of Utrecht, Utrecht University, Utrecht, The Netherlands, Netherlands
SM

Sima Mohammadi, MD

VAC4EU, Netherlands
RG

Raquel Garcia-Esteban

RTI Health Solutions, Barcelona, Spain, Spain
RP

Romin Pajouheshnia

Pharmacoepidemiology and Risk Management, RTI Health Solutions, Barcelona, Netherlands
Katica Boric, PhD, MSc

Epidemiology Project Manager
RTI Health Solutions, Barcelona, Spain
Barcelona, Catalonia, Spain

Co-Author(s)

EP

Elena Palà, PhD

Teamit Institute, Spain

Co-Author(s)

AB

Anna Brutau, PhD

TeamIT, Spain
MH

Margaret Haugh

UMC Utrecht, France
JC

Juan José Carreras Martínez

Vaccine Research Department, Foundation for the Promotion of Health and Biomedical Research in the Valencian Region (FISABIO-Public Health), Valencia, Spain, Spain
AU

Arantxa Urchueguía

Vaccine Research Department, Foundation for the Promotion of Health and Biomedical Research in the Valencian Region (FISABIO-Public Health), Valencia, Spain, Spain
EC

Elisa Correcher Martínez

Vaccine Research Department, Foundation for the Promotion of Health and Biomedical Research in the Valencian Region (FISABIO-Public Health), Valencia, Spain, Spain
MH

María Herrero-Silvestre

Vaccine Research Department, Foundation for the Promotion of Health and Biomedical Research in the Valencian Region (FISABIO - Public Health)
Valencia, Comunidad Valenciana, Spain

Co-Author(s)

TL

Thom Lysen

PHARMO Institute for Drug Outcomes Research, Utrecht, The Netherlands, Netherlands

Presenting Author(s)

JO

Jetty Overbeek

PHARMO Institute for Drug Outcomes Research, Utrecht, The Netherlands, Netherlands

Co-Author(s)

JG

Jordy Gaspersz

PHARMO Institute for Drug Outcomes Research, Utrecht, The Netherlands, Netherlands
Felipe Villalobos

Primary care researcher
Fundació Institut Universitari per a la recerca a l'Atenció Primària de Salut Jordi Gol i Gurina (IDIAPJGol), Barcelona, Spain, Spain
CB

Carlo Alberto Bissacco

Fundació Institut Universitari per a la recerca a l'Atenció Primària de Salut Jordi Gol i Gurina (IDIAPJGol), Barcelona, Spain, Spain
CW

Corinne Williams, PhD

Jansson & Jansson, France
NP

Nicolas Praet

Johnson & Johnson, Belgium
MS

Miriam C.J. Sturkenboom

Department of Data Science and Biostatistics, Julius Center for Health Science and Primary Care, University Medical Center of Utrecht, Utrecht University, Utrecht, The Netherlands, Netherlands
Joan Fortuny, MD PhD

Senior Director Epidemiology
RTI Health Solutions
Barcelona, Catalonia, Spain

Background: The European Commission authorized the Ad26.COV2.S vaccine for individuals aged 18 and older on 11 March 2021 and requested a post-authorization safety study to evaluate the vaccine's safety profile in real-world settings.

Objectives: To assess the association between the Ad26.COV2.S vaccine and 36 prespecified adverse events of special interest (AESIs) within the VAC4EU framework and to compare the risk with mRNA COVID-19 vaccines and unvaccinated individuals. The secondary objective was to assess the association in specific sub-populations, such as immunocompromised individuals.

Methods: This retrospective observational study used data from three European electronic healthcare data sources: PHARMO Data Network (Netherlands), SIDIAP and VID (Spain). The study period spanned from 21 April 2021 to 31 Dec 2022. Self-controlled risk interval (SCRI) and matched cohort (2 comparator cohorts: mRNA vaccine users and unvaccinated individuals) analyses were used to estimate incidence rate ratios (IRRs) and 95% confidence intervals (CIs) using Poisson regression models for each AESI. Where appropriate, results were meta-analysed. Sensitivity analyses and age/gender-stratified analyses were conducted.

Results: The study population included 510,073 recipients of a first dose of Ad26.COV2.S, matched 1:1 to mRNA vaccinees and to unvaccinated individuals. Event rates varied across data sources. For frequently occurring events (>50 events), primary analyses did not suggest a strongly (IRR>2) increased risk for any AESIs. SCRI analysis results suggested increased pooled risks after Ad26.COV2.S vaccination for thrombocytopenia (IRR=1.60; 95% CI: 1.38-1.84), peripheral thrombosis (IRR=1.56; 95% CI: 1.21-2.00), and arrhythmia (IRR=1.27; 95% CI: 1.10-1.47). Among less frequent AESIs ( < 50 events), the results for anaphylaxis, Guillain-Barré syndrome (GBS), and immune thrombocytopenia suggested strongly increased risks but with low precision. Age- and sex-stratified analyses showed differences in risk for conditions such as Bell’s palsy and pulmonary embolism.

Conclusions: This study confirmed the risks outlined by the Ad26.COV2.S vaccine prescribing information for events like thrombocytopenia. However, the robustness of the study was limited by the heterogeneity across data sources due to differences in coding systems and/or availability of hospital data.