Trial overview


A Randomized, Double-blind, Phase 3 Study to Evaluate Safety, Reactogenicity, and Immunogenicity of Co-administration of Ad26.COV2.S and Influenza Vaccines in Healthy Adults 18 Years of Age and Older

The LEGATO study ran from November 2021 until July 2022. 49 people participated.

In this phase 3 study, we investigated the administration of a COVID-19 vaccine (Ad26.COV2.S, Johnson & Johnson) in combination with a flu vaccine. One group received both vaccines on the same day, while the second group had to wait 28 days for the follow-up vaccine.

All participants were over 18 years old, in good general health. They either had not yet received COVID-19 vaccine, or the last dose was administered more than six months ago.

The study compared same-day vaccine administration with administration of both vaccines at 28-day intervals. Participants had to report to the study centre four to five times over a six-month period. In addition, any adverse events were also always followed up by telephone up to a week after each vaccination.

The sponsor of this study was Janssen Vaccines & Prevention B.V. For more scientific background on the study, please visit the official registration database.