A plain language summary of the Janssen COVID-19 vaccine effectiveness and safety as a single dose and with a booster
Abstract
Summary
What is this summary about?
This is a summary of the results of 2 global clinical studies of the Janssen Ad26.COV2.S vaccine against COVID-19. The ENSEMBLE study looked at the effectiveness of a single injection of the vaccine. The separate ENSEMBLE2 study looked at the effectiveness of a booster dose of the vaccine given 2 months after the first dose. In both studies, people received either the vaccine or a placebo. Vaccine effectiveness was evaluated 14 and 28 days after vaccination to allow sufficient time for generation of an immune response.
What were the results?
In ENSEMBLE, compared to the placebo, a single dose of the vaccine prevented:
56% of moderate to severe-critical COVID-19 cases occurring at least 14 days after vaccination
53% of moderate to severe-critical COVID-19 cases occurring at least 28 days after vaccination
75% of severe-critical COVID-19 cases occurring at least 28 days after vaccination
76% of people with COVID-19 from needing to be hospitalized for treatment
83% of COVID-19–related deaths
The vaccine continued to work well for at least 6 months after a single vaccine injection.
In ENSEMBLE2, compared to the placebo, a single dose of the vaccine followed by a booster dose 2 months later prevented:
75% of moderate to severe-critical COVID-19 cases occurring at least 14 days after booster vaccination
100% of severe-critical COVID-19 cases occurring at least 14 days after booster vaccination
In ENSEMBLE2, there were too few cases of COVID-19 to estimate vaccine effectiveness for preventing COVID-19–related deaths or hospitalization. ENSEMBLE2 was done during early 2021, when several COVID-19 vaccines became available by emergency use authorization. For ethical reasons, people could check whether they had received vaccine or placebo and decide whether they could be vaccinated outside of the study. This meant that the researchers could not look at the long-term effectiveness of the vaccine.
In both studies, after receiving the vaccine, some people experienced pain at the injection site, headache, tiredness, muscle pain, and nausea. In most cases, these were mild and went away within a few days. Serious side effects were very rare.
In ENSEMBLE, blood clots, seizures, hives, and ringing in the ears were more common in the people who got the vaccine than in those who got the placebo. These side effects were very rare. In ENSEMBLE2, bleeding, hives, and ringing in the ears were slightly more common in people who got the vaccine than those who got the placebo. In ENSEMBLE2, blood clots were more common in people who got the placebo. At the time of the study, it was not clear if these side effects were caused by the vaccine.
What do the results of the study mean?
The vaccine was effective at protecting against moderate to severe-critical COVID-19 at 14 days after a single injection. Effectiveness was increased by a booster injection given 2 months after the first injection. You can find more detailed information and references in the original articles. Links to these articles can be found at the end of this summary.
Clinical Trial Registration: NCT04505722 and NCT04614948 (ClinicalTrials.gov)
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Link to original articles here and here
Acknowledgments
The authors thank all the participants in the ENSEMBLE and ENSEMBLE2 trials, the staff members at the trial locations, the members of the data and safety monitoring boards, all the investigators at the clinical sites, the authors of the primary manuscripts (ENSEMBLE: Glenda Gray, An Vandebosch, Vicky Cárdenas, Georgi Shukarev, Beatriz Grinsztejn, Paul A. Goepfert, Carla Truyers, Ilse Van Dromme, Bart Spiessens, Johan Vingerhoets, Jerome Custers, Gert Scheper, Merlin L. Robb, John Treanor, Martin F. Ryser, Dan H. Barouch, Edith Swann, Mary A. Marovich, Kathleen M. Neuzil, Lawrence Corey, Jeffrey Stoddard, Javier Ruiz-Guiñazú, Mathieu Le Gars, Hanneke Schuitemaker, Johan Van Hoof; ENSEMBLE2: An Vandebosch, Mathieu Le Gars, Carla Truyers, David Lowson, Ilse Van Dromme, Johan Vingerhoets, Tobias Kamphuis, Gert Scheper, Javier Ruiz-Guiñazú, Saul N. Faust, Christoph D. Spinner, Hanneke Schuitemaker, Johan Van Hoof), and Sadie Van Dyne, PhD, Kurt Kunz, MD, Catherine DeBrosse, PhD, and Jill E. Kolesar, PhD, of Lumanity Communications Inc., for writing and editorial assistance, which was funded by Janssen Global Services, LLC.
Financial & competing interests disclosure
J. Sadoff is a full-time employee of Janssen Research & Development, LLC. K. Hardt, F. Struyf, and M. Douoguih are all full-time employees of Johnson & Johnson. All the authors hold restricted shares and stock options in Johnson & Johnson as part of their remuneration. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.
Information pertaining to writing assistance
Writing and editorial assistance were provided by Sadie Van Dyne, PhD, Kurt Kunz, MD, MPH, Catherine DeBrosse, PhD, and Jill E. Kolesar, PhD, of Lumanity Communications Inc., and were funded by Janssen Global Services, LLC.
Data sharing statement
The data sharing policy of Janssen Pharmaceutical Companies of Johnson & Johnson is available at https://www.janssen.com/clinical-trials/transparency. As noted on this site, requests for access to the study data can be submitted through the Yale Open Data Access (YODA) Project site at http://yoda.yale.edu.
Open access
This work is licensed under the Creative Commons Attribution-NonCommercial 4.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/4.0/
