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Mosaico is a large study that will try to prove whether the experimental vaccine regimen can prevent HIV infection in North America, Latin America, and Europe. To do this, the study will enroll cisgender men and transgender people who have sex with cisgender men and/or transgender people. If Mosaico can show that the study vaccine regimen works, it will be a very important step on the way to finding a safe and effective vaccine for the prevention of HIV.


Your immune system protects you from disease. A vaccine teaches the body’s immune system to prevent a particular infection or fight a specific disease. To develop a vaccine, researchers need to test it in people. A vaccine study tests whether study vaccines are safe (do not cause health problems) and if people’s immune systems respond to the study vaccines. A vaccine study can also be used to find out if vaccines prevent or fight a specific infection or disease. It takes many vaccine studies to produce a safe and effective vaccine.


Protecting the health and respecting the rights of participants are top priorities for everyone in the HIV Vaccine Trials Network (HVTN), Janssen Vaccines & Prevention B.V., part of the Janssen Pharmaceutical Companies of Johnson & Johnson, the National Institute of Allergy and Infectious Diseases (NIAID) of the National Institutes of Health (NIH), and the U.S. Army Medical Research and Development Command (USAMRDC). Clinic staff will provide potential participants with comprehensive information about the study vaccines and procedures, the possible benefits and risks of participating, and the rights they would have as a participant. A person is free to say yes or no to joining the study – the decision is completely up to them.

During the study, the clinic staff will regularly do medical check-ups, HIV testing, and counseling on how to avoid getting HIV. The clinic staff will also ask participants about any social issues they may be experiencing from being in the study and will help to resolve or address them.

There are other independent groups involved in protecting participants’ rights and well-being. The research clinic(s) located near you will be able to provide more information about these groups if you are interested.