In addition to vaccination visits at Day 0 and Day 180, participants will attend study visits at Day 2, 4, 6, 8, 10, 12, 14, 16, 21, 28, 56, 90, 150, 182, 184, 186, 188, 190, 192, 194, 196, 201, 208, 236, 270, and 360. At all study visits, participants will give a medical history and undergo a blood collection; at most study visits, participants will undergo a physical examination. Female participants will have a pregnancy test at select study visits.