Dear Dr G,

I read with interest your argument that men are the weaker sex when it comes to immunity against HPV infection.

I am a woman in my late twenties, well protected against HPV through early vaccination.

However, as a woman, I cannot help but point out that HPV-related cancers affect more than half a million women globally every year.

Although you argue that men also suffer from HPV-induced cancers, the number of male-related cancers is significantly lower than in women.

I would imagine that women suffer more from HPV-related cancers largely because men constantly infect women with the disease.

Am I wrong to assume that transmission of HPV from men to women is higher?

I chose this opportunity to put Dr G on the spot for some clarification.

Is it true that HPV is a sexually transmitted disease?

Do men transmit HPV to women more than women transmit it to men?

Is it also true that men have a higher risk of promiscuity, which puts women at risk?

Lastly, am I also wrong in assuming that men have a higher disease burden of HPV and put more women at risk of cancers?

I look forward to your rebuttal.

Regards

Finger-pointing Florence

Human papillomavirus (HPV) is one of the most common sexually transmitted infections worldwide, and a complex interaction of biological, anatomical, and behavioural factors shapes its transmission dynamics. Although HPV spreads efficiently in both directions between sexual partners, research has explored whether transmission from female to male differs in likelihood compared to male to female transmission.

Transmission of HPV occurs primarily through direct skin-to-skin or mucosa-to-skin contact during sexual activity. In female-to-male transmission, the virus is typically shed from infected mucosal surfaces of the cervix and vaginal lining. These tissues are composed of non-keratinised epithelium, which supports viral replication and can release viral particles into genital secretions. During intercourse, the penile epithelium comes into contact with these secretions, allowing the virus to access susceptible cells, particularly through microscopic abrasions that occur naturally during sexual activity. This continuous shedding from a relatively large mucosal surface area may increase the likelihood that a male partner is exposed to an infectious dose of the virus.

In contrast, male-to-female transmission involves viral presence on the penile shaft, glans, foreskin, or surrounding genital skin. These areas are more keratinised, meaning the outer layer of cells is thicker and less conducive to viral shedding compared to mucosal tissue. However, transmission remains highly efficient because the virus can be transferred to the cervix, especially to the transformation zone, a region where two types of epithelial cells meet and which is particularly vulnerable to HPV infection. Even a relatively small viral inoculum can establish infection in this biologically susceptible area, which helps explain why male-to-female transmission is also clinically significant.

Differences in observed transmission rates between the two directions may partly reflect variations in viral load and shedding patterns. Women with active HPV infection can exhibit higher short-term viral loads in the cervix, leading to increased shedding and potentially a higher probability of transmitting the virus to male partners during that period. Men, on the other hand, often exhibit lower peak viral loads but may carry the virus for longer durations. This persistence may not always produce symptoms, allowing HPV to remain undetected and transmissible over extended periods. As a result, while men may not always transmit the virus as efficiently with a single exposure, their longer infectious period can sustain transmission within a population.

Immune response differences also contribute to these dynamics. Women tend to mount stronger localised immune responses in the cervix and are more likely to clear HPV infections within one to two years. In men, immune responses in penile tissue appear to be less robust or less durable, which may allow the virus to persist longer. This difference does not mean that men inevitably carry high viral loads throughout life, but it does suggest that persistent, low-level infection is more common in men than in women. The absence of routine screening programs for men, comparable to cervical screening in women, further contributes to the perception of prolonged infection, as many cases go undiagnosed.

Behavioural and environmental factors further influence transmission in both directions. Frequency of sexual contact, number of partners, and condom use all play significant roles in determining risk. Circumcision status has also been associated with differences in acquisition and persistence, with uncircumcised men showing higher rates in some studies, possibly due to the microenvironment under the foreskin. Additionally, the presence of microabrasions, coexisting infections, and individual immune status can modify susceptibility.

It is important to emphasise that HPV transmission is fundamentally bidirectional and highly efficient regardless of direction. While certain studies suggest that female-to-male transmission may occur more readily in some contexts due to higher viral shedding from mucosal surfaces, male-to-female transmission is equally important, particularly because of the higher likelihood of persistent infection and serious outcomes such as cervical cancer in women. Therefore, differences in transmission should not be interpreted as a simple imbalance but rather as variations influenced by timing, biology, and context.

Women exhibit higher viral shedding during active infection, increasing short-term transmission risk to men, while men may experience longer persistence of infection, sustaining transmission over time. Both directions of transmission are efficient, and both contribute significantly to the global burden of HPV. Preventive strategies such as vaccination, safe sexual practices, and appropriate screening remain essential for reducing transmission and its associated health consequences. Albert Einstein famously said, “You cannot blame gravity for falling in love!” Dr G is often put on the spot by finger-pointing spouses demanding to find out who should take the blame for the higher risk of HPV transmission. His view is: “It’s definitely not helpful to blame this virus of Love!”