HPV infections drop sharply but experts warn vaccination may not stop cervical cancer

HPV infection has dropped sharply among sexually active young women in England since a national vaccination programme began - but researchers say it is 'uncertain' whether the jabs prevent cervical cancer.

HPV vaccination (Photo: BSIP/Getty Images)
HPV vaccination (Photo: BSIP/Getty Images)

More than 11m doses of HPV vaccine have been administered to girls in England since 2008 as part of an NHS campaign that was extended to boys from September 2019.

According to figures published by Public Health England (PHE), infection rates for HPV 16 and 18 are now below 2% in women aged 16 to 18 - compared with over 15% in 2008. HPV causes 99% of cervical cancers - and HPV types 16 and 18 are responsible for around 80% of cases.

Meanwhile, prevalence of HPV 6 and 11, which cause genital warts, has 'halved' from 'about 7% to 10% between 2010 and 2017, down to 4% in 2018'.

HPV vaccination

However, an analysis of clinical trials on HPV vaccines used in the UK has found that efficacy of the jabs may have been 'overestimated'.

Lead researcher Dr Claire Rees, of Queen Mary University of London, said: 'Trials may have overestimated efficacy by combining high-grade cervical disease with low-grade cervical changes that occur more frequently but often resolve spontaneously without progressing.

'We found insufficient data to clearly conclude that HPV vaccine prevents the higher-grade abnormal cell changes that can eventually develop into cervical cancer.'

The research, published in the Journal of the Royal Society of Medicine (JRSM), looked at 12 published phase two and three randomised controlled efficacy trials of the HPV vaccines Cervarix and Gardasil.

Evidence questioned

Researchers from Newcastle University and Queen Mary University of London highlighted 'methodological problems' in the design of the phase two and three efficacy trials.

The study found: 'It is uncertain whether HPV vaccination prevents cervical cancer. The trials were not designed to detect this outcome, which takes decades to develop. For most outcomes, follow-up data exist for an average of only four or five years.'

Although the researchers found evidence that vaccination prevents low grade abnormal cell changes, they said this is not clinically important because no treatment is given - and that evidence of efficacy against low-grade abnormal cell changes 'does not necessarily mean' vaccination is effective against the types of changes most likely to progress to cancer.

The researchers warned that attendance at cervical screening - which has been found to prevent the vast majority of cervical cancers - remained essential. Co-author of the study, Professor Allyson Pollock of Newcastle University, said: 'We have good evidence that cervical screening significantly reduces the risk of cervical cancer in women regardless of whether they have been vaccinated.'

Cervical screening

The findings came as the charity Cancer Research UK highlighted evidence that less than three-quarters of women invited for cervical screening take it up - with uptake even lower among younger women and in more deprived areas.

The charity also warned that rates of cervical cancer had spiked among women in their 20s - with 12 cases per 100,000 people with a cervix in 2004-2006 compared with 18.5 cases in 2015-2017.

Professor Johnson added: 'More and more young women and men are being vaccinated against HPV, the most recent figures show an increase in people getting screened and most importantly, the number of people infected with the cancer-causing viruses has fallen dramatically.'

He said that cervical cancer could become a 'thing of the past' - with a new, more sensitive screening method rolled out across England from December expected to improve early detection and prevention.

NHS England said that 3.3m people aged 25-64 were tested for cervical cancer over the past year – up 7.7% from the previous year.

Responding to the JRSM study, PHE senior scientist Marta Checchi said: 'Data from the UK suggests that there has been a decline in five high-risk HPV types that cause around 90% of cervical cancer cases. This means that the vaccine programme is on target to dramatically reduce the number of women being diagnosed with high-grade cervical abnormalities and cervical cancer in the future.'

Dr Ravi Pawa, medical affairs director for Gardasil manufacturer MSD, said the company was 'disappointed with the conclusions' in the JRSM study. He said the company believed its findings were 'misleading and could undermine public confidence in the HPV national immunisation programme'.

Dr Pawa added: 'The impact of HPV vaccination is clear. It is recommended by the WHO and is recognised an as integral part of cervical cancer elimination plans.'

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