About Our ENSEMBLE Study

Why is this study being done?
This study is being done to test Janssen’s COVID-19 vaccine candidate, JNJ-78436735, also known as Ad26.COV2.S. Doctors and scientists hope it will prevent or lessen the severity of disease caused by severe acute respiratory syndrome Coronavirus-2 (SARS-CoV-2). This virus causes a disease called COVID-19. The SARS-CoV-2 virus is passed from person to person primarily by small droplets from the nose or mouth when an infected person coughs, sneezes or speaks. Most people who are infected have mild COVID-19 disease such as cough and tiredness, but some people have severe disease and can even die.

Ad26.COV2.S may help to prevent disease by stimulating the human body to form an immune response against the virus that causes the disease. This defensive response is a way your body fights infections. This study will help determine if Ad26.COV2.S is safe for humans and protective against COVID-19 disease.

The main purposes of this study are to see

  1. If the Ad26.COV2.S vaccine is safe
  2. To learn more about the side effects caused by the Ad26.COV2.S vaccine
  3. If the Ad26.COV2.S vaccine helps to prevent or lessen the severity of COVID-19.

In this study, half of the participants will get a placebo instead of the Ad26.COV2.S vaccine. The placebo looks just like the Ad26.COV2.S vaccine and is given the same way: by injection (shot). But the placebo contains no active vaccine. Using a placebo in the study allows researchers to see potential differences between the investigational vaccine and the placebo. The placebo in this study will be sodium chloride, also known as saline (saltwater).

Throughout this document, when the words “study vaccine” are used, they can mean Ad26.COV2.S or placebo.

General Information about the study
Up to 60,000 participants around the world will take part in this study.

Participants who join the study will be in it for about 2 years. During the study staff will collect blood samples, saliva samples and nasal swabs. If you become sick with COVID-19 (you cannot get COVID-19 from the vaccine), the study staff will monitor you daily and request that you provide extra nasal swabs and saliva samples.

During the study, the company may learn new information about the study vaccine such as risks. Your study doctor will tell you as soon as possible about any new information that might make you change your mind about being in the study. It is possible that you will not benefit from participating in this study because we do not know if the vaccine works to prevent COVID-19 disease. There is a small chance you may have a bad reaction to the vaccine or that the vaccine may make you sicker if you do get COVID-19.

The study will be conducted in two stages for each age group. The first group consists of 2000 participants aged 18-59 who do not have other health conditions. After they have received the injection of the study vaccine or placebo and have been observed for 3 days following the injection, all the remaining participants in that age group will be enrolled. The same process will be followed for the group aged 60 and older. Participants will be informed whether they are in the first group or in the second group. If you do not qualify for the first group of participants due to other health conditions, you may still qualify for the second group of participants.

You may choose to not participate in this study, in which case you will not lose access to any medical care or other benefits already available to you or that you may need in the future.

In addition to funding from Johnson & Johnson, this study is co-funded by Biomedical Advanced Research and Development Authority (BARDA) and the National Institute of Health, both of which are part of U.S. Department of Health and Human Services.
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For additional information about the ENSEMBLE Study, please click here.

For additional details regarding the ENSEMBLE Study protocol, please click here.*

* This link will take you to the version of the study protocol as of September 23, 2020. Please note any amendments and updates to the protocol will be made according to local requirements and relevant information from the protocol will be available on regional registries such as

Learn more about the innovative ways the company is mobilizing to help combat the global outbreak caused by the novel coronavirus.
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