Few viruses are as widespread – and sometimes misunderstood – as the human papillomavirus, or HPV. It’s so common that most of us – up to 80% – will encounter it at some point in our lives, often without even realising it. Understanding HPV matters, given that it is linked to several types of cancer.

Scientists have identified more than 200 types of HPV, making it one of the most diverse viral families known – and a complex one at that. Many strains are low risk, causing either no symptoms or benign warts. HPV types 1, 2 and 4, for instance, are responsible for the common skin wart. Many will have experienced these, including the familiar verruca (plantar wart) picked up at swimming pools.

Some strains, such as HPV 6 and 11, cause genital warts – small growths that appear on the genitals or around the anus. Treatments such as creams, surgical removal or freezing can get rid of the visible warts, but they don’t remove the virus itself. This means the virus can still be passed to sexual partners until the body’s immune system clears it.

Most seriously, certain types of HPV – particularly 16 and 18 – have known links to cancer. They belong to a group of about 14 high-risk strains that can enter human cells and damage their DNA. This damage interferes with the cells’ normal controls on growth and division, which can lead to the development of cancer.

Repeated or persistent infection with these strains increases the risk of developing cancer. So, too, does smoking, which reduces the ability of the immune system to clear the virus.

Because HPV comes in so many forms – from harmless skin warts to strains linked with cancer – it’s easy to see how myths and confusion can take hold. To separate fact from fiction, here are five key points that everyone should know about the virus.

1. HPV is not just associated with cervical cancer

While cervical cancer remains the most recognised HPV-related malignancy, the virus is also linked to cancers of the vulva, vagina, anus, penis, mouth and throat. Emerging evidence suggests some types may also contribute to developing skin cancer.

This broad cancer risk explains why the widely available HPV vaccine is recommended for both sexes. The vaccine’s ability to prevent HPV infection makes population-wide immunisation beneficial, as transmission may occur between heterosexual and homosexual partners alike.

2. You don’t need to have symptoms or genital warts to pass the virus on

HPV can remain on the skin for months before the immune system clears it, allowing transmission through contact even before genital warts appear and after they’ve been treated. This is why condoms should be used for at least three months after visible warts have resolved.

A condom in gold packaging.
A condom should still be used three months after genital warts have resolved. AtlasStudio/Shutterstock.com

3. HPV transmission can occur from more than just vaginal or anal sex

Oral and throat cancers can develop following HPV infection acquired through oral sex. The incidence of mouth and throat cancer is increasing worldwide, with oral sex now the most significant behavioural risk factor. Using condoms during oral sex can help reduce this risk.

HPV can also spread through the use of sex toys. One study highlighted the ability of transmissible HPV to remain on sex toys and the need to develop proper hygiene practices for cleaning, and avoiding shared use.

4. Condoms are not 100% effective at preventing spread

Condoms can lower the risk of HPV transmission, but they can’t offer full protection, as uncovered skin can still carry the virus.

This is why many sexually active people will come into contact with a strain of the virus at some point in their lives, even when practising safe sex.

5. Even vaccinated women need to have smear tests

Current HPV vaccines target the main high-risk virus types but cannot cover all cancer-causing strains, or treat existing infections. In rarer cases, cervical cancer can also arise without HPV infection. This is why women aged 25 to 64 are still invited for cervical screening every five years, even after vaccination.

Women should also seek urgent medical review for other indicators of cervical cancer. These include pain or bleeding after sex, bleeding between periods or after menopause, and changes in vaginal discharge.

Even though the HPV vaccine is widely available, uptake has dropped in some areas. The COVID pandemic disrupted routine vaccination programmes, while misinformation about the vaccine’s safety and effectiveness has shaken trust. In some places, low awareness of HPV’s link to different cancers – and of the need to vaccinate boys as well as girls – has also made public understanding more difficult.

The World Health Organization has set a target of fully vaccinating 90% of girls by age 15 by 2030. At present, only about 48% of girls worldwide are fully vaccinated, so there is more work to be done.

Although HPV is often harmless, the potential consequences of some strains are too significant to ignore. But no one should be fearful of an active sex life. For those eligible for the HPV vaccine, protection is not just for the individual, but also for future sexual partners who could otherwise be exposed. By staying informed and taking preventative measures, we can reduce the effect of this common virus and keep ourselves and others safer.

This article is republished from The Conversation, a nonprofit, independent news organization bringing you facts and trustworthy analysis to help you make sense of our complex world. It was written by: Dan Baumgardt, University of Bristol

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Dan Baumgardt does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.