Trial overview


A Randomized, Double-blind, Placebo-controlled Phase 3 Study to Assess the Efficacy and Safety of Ad26.COV2.S for the Prevention of SARS-CoV-2-mediated COVID-19 in Adults Aged 18 Years and Older

The ENSEMBLE-2 study is investigating the safety and efficacy of a COVID-19 vaccine (Ad26.COV2.S, Johnson & Johnson). This phase 3 study was sponsored by Janssen Vaccines & Prevention B.V.

The study started at the CTC in January 2021 and will end by summer 2023. That means participants will be in the study for about 26 months, with a total of at least seven visits to our study centre. Participants with any complaints after vaccination or participants who did contract COVID-19 infection were followed up closely.

We included more than 600 participants at the CTC in this study. Participants had to be at least 18 years old, without any acute or chronic condition.

For more scientific background on the study, please visit the official registration database,