Vaccination against human papillomavirus (HPV) types 16 and 18 protects women against cervical cancer associated with these two common phenotypes.
A recent study by Oakshott and her colleagues from the UK has found that 18.5% (95% CI 17-20%) of nearly 2,200 women attending a sexually transmitted infection (genitourinary medicine) clinic were positive for HPV types associated with cervical cancer in samples taken from vaginal swabs. These included 327 women (15%) who were positive for HPV genotypes not covered by the current vaccines currently in use.
By sampling twice a median of 16 months apart the authors were able to provide an annual estimate of new infections (incidence) of nearly 13% of carcinogenic genotypes. Reporting two or more sexual partners in the previous year and concurrent Chlamydia trachomatis or bacterial vaginosis were independent risk factors for prevalent vaginal HPV infection.
Of the 143 women with baseline carcinogenic HPV that provided samples later 14% were infeceted by the same HPV genotype.
The study was performed before the introduction of immunisation against HPV types 16 and 18 for schoolgirls. It highlights the continued need to screen women for cervical cancer.