Previous research has shown that vaccination can prevent HPV infection and the development of precancerous changes. It is reported that the effectiveness of a vaccine in the prevention of invasive cancer is so convincingly demonstrated by scientists for the first time.
Women who were vaccinated against HPV at a young age have a significantly lower risk of developing cervical cancer than those who are not vaccinated. Study published at New England Journal of Medicine.
What we knew about the effectiveness of the HPV vaccine
The most important goal of developing a vaccine and introducing immunization against human papillomavirus (HPV) was the prevention of infection with oncogenic HPV types and the prevention of the cervix. By the end of 2019, the national vaccination program approved 124 countries.
The media have repeatedly reported on the effectiveness of the vaccine. However, there have not been large studies previously conducted in which scientists have focused specifically on the incidence of cervical cancer. This is due to the fact that relatively little time has passed since the start of vaccination programs. Just one study concerned this question, but there were not enough participants to objectively assess the effect of the vaccine.
The prevalence of papillomavirus infection of the mouth and pharynx among unvaccinated men in the United States has decreased by 37%. Scientists believe that this was due to the emergence of population immunity due to the massive vaccination against the human papillomavirus (HPV).
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Previous studies have shown that HPV vaccination protects against HPV infection, genital warts, and precancerous changes cervix… These data spoke only indirectly that the vaccine can prevent invasive cancer. Invasive cancer called a malignant tumor that has gone beyond the tissues in which it formed and began to penetrate into neighboring healthy tissues. In this case, we are talking about cervical cancer, which has grown outside the mucous membrane.
What do we know about the effectiveness of the vaccine now
“We have been able to show for the first time at a population level that HPV vaccination protects not only against cellular changes that may be precursors of cancer, but also specifically against invasive cervical cancer.” said Jiayao Lei of the Karolinska Institute in Sweden, co-author of the study. He added that such an effect of the vaccine has long been suspected, but it has not been possible to confirm it in a large national study.
In the new study, researchers followed nearly 1.7 million women between the ages of 10 and 30 for 11 years. More than 500,000 of them received the HPV vaccine, most of them under the age of 17. During the study, cervical cancer developed in 19 vaccinated women and 538 unvaccinated women, which corresponds to 47 and 94 per 100 thousand, respectively.
After additional calculations, it turned out that women who were vaccinated before the age of 17 had an 88% lower risk of cervical cancer than those who did not receive the vaccine. In women vaccinated at the age of 17-30, this risk was 53% lower.
Scientists noted that the effectiveness of the vaccine in young girls is higher, most likely due to the fact that they were less likely to face HPV infection. Vaccination cannot protect after infection.
Overall, the new data support expectations about the value of HPV vaccination in preventing cervical cancer, the study authors said.