Co-infection with HPV types from the same species provides natural cross-protection from progression to cervical cancer Rafal S Sobota126*, Doreen Ramogola-Masire345, Scott M Williams2 andNicola M Zetola345* Abstract Background The worldwide administration of bivalent and quadrivalent HPV vaccines has resulted in cross-protection against non-vaccine HPV types. Infection with multiple HPV types may offer similar cross-protection […]