A common infection
HPV is a very common virus, and the CDC notes that almost everyone who is not vaccinated will be infected at some point. It spreads through close skin-to-skin contact, including vaginal, anal and oral sex, and it can be passed on by people who have no signs of infection. About 9 in 10 infections clear on their own within two years.
HPV types and cancer risk
There are many types of HPV: some cause genital warts, while others can cause cancer. Infections that persist can lead to cancers of the cervix, vagina, vulva, penis, anus and back of the throat. WHO reports that HPV types 16 and 18 cause around 76% of cervical cancers. Precancerous changes can take 15 to 20 years to become cancer, or 5 to 10 years in women with weakened immune systems, such as women with untreated HIV. Women living with HIV are six times more likely to develop cervical cancer than women without HIV.
Screening with an HPV test
HPV-based screening looks for high-risk types of the virus in a sample from the cervix or vagina, so it can identify women at risk before abnormal cells develop. WHO recommends screening with a high-performance test every 5 to 10 years from age 30, or every 3 to 5 years from age 25 for women living with HIV, and considers self-collected HPV samples as reliable as clinician-collected samples.
In Australia, the National Cervical Screening Program invites women and people with a cervix aged 25 to 74 to have a Cervical Screening Test every five years through their healthcare provider. Participants can choose to collect their own sample.
Understanding the result
If HPV is not found, the next test in the Australian program is due in five years. A positive HPV result does not mean cancer. It means a high-risk type is present and further assessment is needed. Depending on the type of HPV detected, this may be a clinician-collected cervical sample to examine the cells, or referral to a specialist for colposcopy, a magnified examination of the cervix during which small tissue samples (biopsies) can be taken. Precancerous changes found in this way can be treated, for example by thermal ablation, cryotherapy or loop excision.
Vaccination and elimination
All licensed HPV vaccines protect against types 16 and 18. WHO lists vaccination of girls aged 9 to 14, before they become sexually active, as a priority, given as one or two doses depending on the national schedule. The WHO elimination strategy sets three targets for 2030: 90% of girls fully vaccinated by age 15, 70% of women screened with a high-performance test by age 35 and again by 45, and 90% of women with precancer or cancer receiving treatment.