As part of our Vaccine Engagement Day initiative, we are posting a series of blogs exploring the impact vaccines have had in a number of areas. In our first post of the series, we are exploring the Human Papilloma Virus (HPV) vaccine.
Cervical cancer is one of the most common cancers in women globally, with around 660,000 new cases reported each year. There are approximately 3,250 new cases in the UK each year, with incidence highest in women in their early thirties. However, in low- and middle- income countries where access to vaccinations and screening are limited, cases are much higher.
The vast majority of cervical cancer cases are caused by persistent human papillomavirus (HPV) infection. HPV is a common sexually transmitted viral infection, which affects the genital area, throat & skin – with infection in these areas associated with increased risk of developing genital warts as well as cervical, anal, penile and some head and neck cancers. Two strains in particular, HPV 16 and HPV 18, are responsible for approximately 70% of cervical cancer cases. HPV is so common that nearly 80% of sexually active individuals will contract it at some point, often without immediate symptoms.
The hidden culprit
The idea that cancer could be caused by a virus was first proposed in the 1930s, when Dr Richard Shope theorised that papillomavirus infection could cause warts and cancers in animals. This revelation inspired German virologist Professor Harold zur Hausen to investigate the role of viruses in human cancer. By testing cervical cancer samples, multiple strains of HPV were identified. It later became clear that a large proportion of cervical cancer samples were associated with HPV 16 and 18 infections. Building on this discovery, researchers developed vaccines targeting high-risk HPV strains, eventually leading to the UK’s first HPV vaccination programme. Professor zur Hausen was awarded a Nobel Prize in 2008 for his contributions.
Following the discovery of these high-risk HPV strains, the exact mechanism by which HPV causes cervical cancer has been unravelled. HPV acts by infecting basal epithelial cells. During infection, HPV integrates into the host cell’s DNA, disrupts cell growth, and deploys mechanisms to escape the host immune response. Upon infection, HPV expresses two viral oncoproteins, E6 and E7, which interfere with tumour-suppression mechanisms in the cell, contributing to the development of cancer. These changes result in abnormal cell growth and the formation of precancerous lesions. If left undetected, these abnormal cells can eventually develop into invasive cancer, though this process may take many years.
Fighting back against HPV
Unlike most cancers, the fact that almost all (99.8%) cervical cancer cases are caused by persistent HPV infection poses a unique opportunity to prevent the development of disease. Following decades of research, the first vaccine preventing HPV infection was licensed in the UK & USA in 2006. Since then, multiple HPV vaccines have been successfully developed, protecting against various strains of the virus. Following the successful development of vaccines targeting high-risk strains of HPV, the first UK HPV vaccination programme was introduced in 2008. The programme was offered in schools for girls aged 12–13 and initially required three doses of the vaccine. From September 2019, based on evidence and advice from the Joint Committee on Vaccination and Immunisation (JCVI), the HPV vaccination programme was extended to include boys aged 12-13 to protect them against HPV-related cancers and reduce the spread of the virus.
Later studies have demonstrated that the HPV vaccine is effective in providing protection after just one dose. This led to the JCVI recommending a change in the national vaccination programme in 2022/23, making it easier for young people to get fully vaccinated. A single dose of the HPV vaccine is now offered in schools to all children aged 12–13; it is also free to receive from the NHS until the age of 25 and is offered to those at risk of being infected with HPV by sexual health clinics. In the long-term, it is predicted that the current HPV vaccine will reduce cases of women’s cancer and HPV attributable deaths by a further 16% and 9%, respectively.
What impact has HPV immunisation had in the UK?
Over a decade after HPV immunisation programmes were introduced across the UK, researchers were finally able to assess the vaccines’ impact on cervical cancer cases. In the first study of its kind, researchers showed that immunisation against HPV 16 and 18 reduced the number of cervical cancer cases in England by nearly 90% in women who were vaccinated. It is estimated that this programme prevented approximately 450 cervical cancers and 17,200 cases of precancerous lesions during this time. A more recent study from Public Health Scotland, published in 2024, demonstrated that no cervical cancer cases had been detected in women vaccinated at the recommended timepoint against HPV since the schools’ immunisation programme began in 2008. It is important to note that in addition to the success of the HPV vaccines in eliminating cervical cancer, changes have also occurred surrounding cervical screening. Eligible individuals are first offered cervical screening at the age of 25, and subsequently, routine screening every three years. It is estimated that cervical screening saves approximately 5,000 lives a year by preventing the development of cervical cancer.
Despite the success in moving towards the elimination of cervical cancer, recent data from England have shown that in 2024 HPV vaccine uptake was at its lowest since before the Covid-19 pandemic. In 2023–24, only 72.9% of female and 67.7% of male year 8 students received the HPV vaccine. Due to disruptions in the schools’ HPV vaccine schedule during the Covid-19 pandemic, catch-up dosing against HPV is required to eliminate preventable cancers. However, only 94 (62.2%) local authorities have completed catch-up activity. Further investigation into a decline in HPV vaccine uptake has suggested this may be due to a lack of awareness around schools’ HPV vaccination programmes as well as a lack of clarity around eligibility, especially around boys being able to receive the HPV vaccine. It is also notable that in the UK there is variation in vaccine uptake and screening coverage amongst certain communities. For example, the most deprived quintile of England has a 65% higher incidence rate of cervical cancer compared with the least deprived. To eliminate preventable cancers, it is vital that momentum continues to increase the uptake of the HPV vaccine and continued attendance to cervical screenings.
What does the future hold for the prevention of cervical cancer?
Following the successful development of HPV vaccines, by 2019, 100 countries had incorporated HPV immunisation into their regular vaccine schedule. In 2020, the World Health Organization (WHO) published a global strategy to eliminate cervical cancer following the success of HPV immunisation in high-income countries. This strategy highlighted global inequities in HPV vaccine availability, cervical cancer screening and treatment management in low- and middle-income countries. In these areas, incidence is nearly twice as high, and death rates are three times as high compared with higher income countries. If achieved by 2030, the targets set by WHO would result in over 62 million deaths from cervical cancer being averted worldwide over the next 100 years. This goal was aligned in the UK by NHS England which outlined its ambition to eliminate cervical cancer by 2040, with an incident rate of below 4 per 100,000 cases.
The HPV vaccine has proven to be a game-changer in the fight against cervical cancer. By effectively preventing the high-risk HPV strains responsible for most cervical cancer cases, the vaccine has led to significant declines in infections, precancerous lesions, and, most importantly, cancer diagnoses. As vaccination efforts continue to expand worldwide, we move closer to a future where cervical cancer is much rarer and, in many cases, preventable. The success of the HPV vaccine highlights the incredible impact of scientific advancements and public health initiatives in cancer prevention.
By Dr Hannah Tompkins
External Affairs Intern