Neutralization of non-vaccine human papillomavirus pseudoviruses from the A7 and A9 species groups by bivalent HPV vaccine sera

► We examined neutralizing antibody in girls immunized with bivalent HPV vaccine. ► Antibody cross-reactivity dependent on response to vaccine types. ► Significant cross-reactivity against HPV31, HPV33, HPV45. ► Cross-reactive levels are low at <1% of vaccine type antibody responses. ► Potential role for cross-reactive antibodies as surrogate of protection.