(359) Safety of the Janssen COVID-19 vaccine (JCOVDEN) using VAC4EU European Healthcare Data Sources: Methods and Results of the Second Study Feasibility Assessment

Background: As part of the lifecycle benefit-risk assessment of vaccines, we are conducting a post-authorisation safety study (PASS) utilizing real-world data to characterize and assess the safety profile of JCOVDEN.

Objectives: As part of the JCOVDEN PASS, this second feasibility study aimed to i) describe JCOVDEN patterns of use compared to other COVID-19 vaccine brands, ii) characterise vaccinated individuals, iii) describe follow–up time and reasons for censoring, and iv) conduct time-to-onset analyses for 36 pre-specified adverse events of special interest (AESIs).

Methods: This retrospective observational study used electronic healthcare data from two European countries (the Netherlands [PHARMO Data Network] and Spain [VID, SIDIAP]) collaborating in the VAC4EU consortium. Data were harmonised across data sources using the ConcePTION common data model. Analytical steps included syntactic and semantic harmonisation of data, implementation of the epidemiological study design, and statistical analysis.
Descriptive statistics were used. Unadjusted incident rates (IRs) of AESIs (per 10.000 person-years) were compared to 1st feasibility assessment and the 2018 background rates published in the ACCESS study.

Results: A total of 510,145 individuals received the first dose of the JCOVDEN vaccine in line with ECDC Vaccine Tracker data for the Netherlands and Spain. The first dose was predominantly administered to those aged 40-49 in SIDIAP and VID and 20-29 in PHARMO; female vaccinated individuals were 36.9% in PHARMO, 44.1% in SIDIAP, and 46.2% in VID. Between 0.4 and 1.2% of vaccinated individuals were pregnant across data sources. Most individuals (>65%) received a COVID-19 mRNA vaccine as a second dose approximately six months after initial vaccination with JCOVDEN.

The AESIs were identified using disease codes (ICD10CM, ICD9CM, ICPC) and free texts and our feasibility analyses identified clinically relevant AESIs. Compared to the 1st feasibility assessment, this assessment exhibits improved specificity in centralised code lists, programming enhancements, and refined study population selection. IRs of AESIs were also consistent with 2018 ACCESS background rates.

Conclusions: This feasibility study identified over half a million individuals vaccinated with JCOVDEN. While the data from the three data sources are suitable for the planned final analysis, statistical power may be limited for very rare AESIs for the final comparative analysis.