A booster cancer vaccine comprised of a modified, replication-defective, vaccinia virus Ankara (MVA) Bavarian Nordic (MVA-BN) strain encoding the oncogenic human papillomavirus types 16 (HPV16) and 18 (HPV18), with potential immunostimulating and antineoplastic activities. Upon intramuscular administration of MVA-vectored HPV16/18 vaccine JNJ-65195208, and after the administration of the prime vaccine(s) adenovirus serotype 26 (Ad26)-expressing HPV16 vaccine JNJ-63682918 and/or Ad26-expressing HPV18 vaccine JNJ-63682931, this vaccine further stimulates the host immune system to mount a cytotoxic T-lymphocyte (CTL) response against tumor cells expressing HPV16/18 proteins, resulting in tumor cell lysis. HPV16/18 infection plays a key role in the development of a variety of cancers.