Human papilloma virus, which is sexually transmitted, can cause cervical cancer as well as anogenital warts. Data from high-income countries shows vaccination has led to an 83% reduction in HPV infections in 15- to 19-year-old girls over five to eight years. Among women aged 20 to 24, infections are down 66%.
Major reductions also took place in anogenital warts and precancerous lesions, which can be the precursor to cervical cancer. HPV vaccination has only been available for 10 years, so the effect on cancers is not yet known, although it is predicted they will also drop significantly.
The research, published in the Lancet medical journal, will bolster the determination of the World Health Organization, which is setting goals for reducing the number of cases of cervical cancer to no more than four per 100,000 population, below the threshold for a rare disease.
Prof Marc Brisson from Laval University, one of the authors, said: “We’re working with the WHO, using mathematical modelling to determine when elimination would occur.
“We don’t have a precise date. High vaccine coverage has to be maintained. It depends on the country and how much coverage and screening there is, and how many cohorts have been vaccinated.”
Australia, where takeup of the vaccine is almost as good as in the UK, is now working towards elimination. “There could be elimination in decades,” said Brisson.
The study shows vaccinating multiple cohorts of girls at different ages, as took place at the beginning of the programme in the UK, helps bring down HPV infection rates. HPV vaccination was introduced for girls aged 12 in schools in the UK, but a catchup programme allowed girls up to the age of 18 to be vaccinated as well.
From September, the UK will begin offering HPV vaccination to boys, which will further reduce the pool of the virus. The study shows older women and boys and men already get some protection from HPV-related diseases from the vaccination of girls.
Dr David Mesher, a principal scientist at Public Health England, said it was too early to see data on a drop in cervical cancer cases because this takes years to develop. At the moment, the burden of cervical cancer is in women who were too old to be vaccinated – the vaccine is not very effective in women who are sexually active and may have already been exposed to the virus.
But he said: “There is every indication we will see it in the near future. We will start relatively soon to see an impact in younger women.” Brisson said there could be a noticeable drop in cervical cancers within 10 years.
The paper looked only at studies carried out in high-income countries where there has not been opposition to the vaccine. In Denmark, Ireland and a few other European countries, a scare over claims that the jab had caused girls to become ill, fuelled by TV documentaries showing them in wheelchairs with ME-type symptoms, led to a drop in vaccination rates. In Japan, the vaccination programme was suspended.
There is also no data from less wealthy countries, where there are the highest numbers of women with and dying from cervical cancer. In 2018, there were 569,000 cases of cervical cancer worldwide and 313,365 deaths, 80% of which were in these countries.
“What we see is that in many low- to middle-income countries, there is no vaccine at all,” said Brisson. “These are the countries with the highest burden of cervical cancer. The results show that the vaccines are working towards preventing cervical cancer, so I hope that we will be able in coming years to increase vaccination coverage in many of the countries that need it most.”
Low-income countries have been slow to introduce the vaccine and their monitoring systems are not good enough to produce useful data, said Mark Jit, a professor of vaccine epidemiology at the London School of Hygiene and Tropical Medicine.
“If we are to realise the dream of eliminating cervical cancer then we will need to ensure that our limited supplies of vaccines are prioritised to the countries that need them the most,” he said.
Robert Music, the chief executive of Jo’s Cervical Cancer Trust in the UK, said the drop in infections was “truly exciting news”.
He added: “We’re lucky to have the HPV vaccination programme here in the UK, and this study supports the imminent rollout of the gender-neutral HPV vaccine. However, this study also shows the urgent need for all countries without a vaccination programme to be supported in establishing one.
“This study furthers the growing evidence to counteract those who don’t believe that this vaccine works, which is now extremely encouraging. We sincerely hope this will boost public faith in the HPV vaccine so that more lives can be saved and we get closer to a world where cervical cancer is a thing of the past.”
More about: cancer