A Trial to Evaluate the Safety and Immunogenicity of Ad26-ENVA and Ad35-ENV HIV Vaccines in Healthy HIV-uninfected Adult Volunteers

The study is a randomized, double-blind placebo-controlled trial assessing the order of
vector priming and boosting (Ad26 versus Ad35), the timing of boost (3 versus 6 months) and
the homologous versus heterologous regimen at the 3-month time interval. Groups A-D will be
enrolled in Boston, MA, USA, Groups E-H will be enrolled at the East African Clinical
Research Centres (currently under regulatory and/or ethics review), and Groups I-L will be
enrolled at the South African Clinical Research Centres (currently under regulatory and/or
ethics review).

Volunteers will be screened up to 56 days before vaccination and will be followed for 12
months after the second vaccination.

Approximately 212 volunteers will be randomized to receive either vaccine or placebo within
a group (A-L); Groups A-D, Groups E-H and Groups I-L will be randomized separately. Up to 7%
over-enrolment (approximately 15 volunteers) will be allowed to facilitate enrolment.