Young women who were vaccinated against the human papillomavirus (HPV) in their teens with an older GlaxoSmithKline product called Cervarix had up to an 87% lower risk of developing cervical cancer linked to the virus, a long-running English study has found.
When the vaccinated women were in their 20s, those who had received the series of shots between ages 12 and 13 had cervical cancer rates that were 87% lower than unvaccinated women who had been screened for the malignancy.
The cancer rate was 62% lower when the doses were given between ages 14 and 16 and reduced by 34% in women vaccinated between ages 16 and 18, researchers reported in The Lancet medical journal.
Rates of a precancerous condition were reduced by 97% when the shots were given at ages 12 and 13, the study also found.
The findings "should greatly reassure those still hesitant about the benefits of HPV vaccination", the researchers said.
The study, funded by Cancer Research UK, looked at registry data from January 2006 to June 2019 on women who had been screened for cervical cancer between ages 20 and 64, including women who received the Cervarix vaccine after it became available in 2008.
During the nearly 13-year period, roughly 28,000 diagnoses of cervical cancer and 300,000 diagnoses of a precancerous condition called cervical intraepithelial neoplasia (CIN3) were recorded in England, data showed.
The young women who were vaccinated had around 450 fewer cases of cervical cancers and 17,200 fewer cases of CIN3 than expected in unvaccinated women of the same age.
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"We hope that these new results encourage uptake as the success of the vaccination programme relies not only on the efficacy of the vaccine but also the proportion of the population vaccinated," said co-author Kate Soldan of the UK Health Security Agency.
Cervarix, developed by GSK, protects against two HPV types that are responsible for roughly 70% to 80% of all cervical cancers.
Since September 2012, Merck's quadrivalent vaccine Gardasil, which protects against four HPV types linked to cervical and head and neck cancers, has been used in England instead of Cervarix.
GSK also stopped selling Cervarix in the US due to low demand with Gardasil dominating the world's most lucrative market.
Cervical cancer is rare in young women. Follow-up as women grow older is needed to fully assess the vaccines' impact.
The director of the Public Health National Immunisation Office Ireland described the study as "really good news".
Dr Lucy Jessop told RTÉ's News at One that Irish girls are inoculated at the same age as those covered by this study, which is between 12 and 13 years.
She said that since 2019, boys have also been offered the HPV vaccine, which protects against mouth, throat and other cancers.
Dr Jessop said the study "underlines how important it is for parents to come forward and vaccinate their children in first year of secondary school".
She said that Ireland is using vaccines that are even more effective than the one covered by this study and that offer protection against a broader range of cancers and genital warts.
She said that in 2019 there was a 82% uptake of first dose and 76% uptake of second doses, which is consistent with WHO targets.
She said that some children who may have missed out on HPV vaccinations during school closures can still be vaccinated.