14,480 new cases of invasive cervical cancer are reported in the US every year, the vast majority of which is caused by a family of oncogenic HPV viruses. Since 2007, HPV vaccination has been recommended to prevent this sexually transmitted infection and its serious consequences. An English study showed that the HPV vaccination campaign has cut down the incidence of precancerous lesions and reported cancers in young women.
The good results of the vaccination campaign against human papillomavirus (HPV), sexually transmitted viruses that cause some cases of cervical cancer, are confirmed. Gardasil 9 is effective against 9 different HPV types (6, 11, 16, 18, 31, 33, 45, 52, and 58) while Cervarix is only effective against 2 types ( 16 and 18). After the first vaccinations with Cervarix, positive results were quickly observed on the number of HPV infections and the incidence of precancerous lesions in women.
97% fewer precancerous lesions in very young girls
Now, a British study in The Lancet showed that one injection of the Cervarix vaccine – the most widely administered vaccine in the UK at the time of the study – significantly reduced the number of reported cases of cervical cancer and cervical intraepithelial neoplasia class 3, a deep lesion preceding cancer. The protection offered by the vaccine depends on the age of the girls. The reduction in reported cases of cervical cancer in vaccinated girls aged 16-18 years is 37%, in girls aged 14-16 years 62% and in girls aged 12-13 years 87% compared to unvaccinated girls. A similar phenomenon was observed for deep cancer precursors: the vaccine reduced them by 39% in 16 to 18 year-olds, by 75% in 14 to 16 year-olds, and by 97% in 12 to 13 year-olds.
The study focused on very young girls, but to know whether the benefits of vaccination persist over time, follow-up over several years is needed. HPV vaccination is recommended for girls and boys aged 11-14 years with a two-dose protocol. Repeat vaccination is possible for 15 to 19 year-olds with three doses. Currently in the US Gardasil is approved for both men and women up to the age of 45. Keep in mind that the current study was done with Cervarix which only protects against two strains of HPV16 and 18. However, Gardasil 9, which is the one used mostly in the US protects against nine strains so the results published in The Lancet do not apply to it. It would be however not too far-fetched to infer that the results for Gardasil 9 would be even better than the results accomplished with the Cervarix vaccine.
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