Vaccinating young women against human papillomaviruses is effective. In New Mexico, precancerous lesions and abnormalities have been halved.
The papillomavirus vaccine is effective. Vaccinating young girls widely is also. An American study evaluated the impact of this gesture on abnormalities in the tissue of the cervix. Carried out at the level of the inhabitants of New Mexico, it shows the positive effect of vaccination. In this state where the coverage is rather good, the precancerous lesions have fallen significantly. This is the conclusion of this work published in the JAMA Oncology.
Fewer precancerous lesions
The human papillomavirus vaccine is at the heart of heated controversy. It is the subject of suspicion of severe side effects, which have not yet been demonstrated. Its detractors also blame it for a lack of evidence of effectiveness against cervical cancer. There is indeed a delay between vaccination and obtaining tumor data. Australia recently provided evidence of a reduction in genital warts. It is the turn of the United States to bring their contribution to the edifice.
The study conducted by the University of New Mexico looked at the papillomavirus surveillance registry and collected data from 2007, when the vaccine was approved, until December 31, 2014. In total, nearly 220,000 women were involved. Protection against HPV is indeed effective: in young patients aged 15 to 19, the diagnoses of smear abnormalities have declined significantly. Stage 1 lesions have increased from 3,500 cases per 100,000 women to 1,600.
The decline is similar in stage 2 lesions. For women aged 20 to 24 years, the incidence of moderate stage precancerous lesions also decreases. It goes from 1,027 cases per 100,000 women to 627. Conversely, grade 3 lesions increase in women aged 25 to 29 years.
Vaccine coverage and strains
The authors of the study do not fail to specify that “the reduction in incidence was more pronounced than expected”. Several factors explain these good results, starting with immunization coverage in the state of New Mexico. It is certainly insufficient, since only 40% of young women have received the three regulatory doses, but it remains rather good. By way of comparison, barely 16% of French women received the same treatment.
Thanks to this strong participation, indirect protection can be observed: vaccination also benefits those who have not been vaccinated. This is the principal of collective immunity. To achieve this, more than 70% of young women would need to protect themselves against papillomaviruses. The researchers also underline the impact of existing products, which target several strains of HPV causing cancers of the cervix, the anus and the ENT sphere. Indeed, Gardasil targets four genotypes, Cervarix two: 16 and 18. These are responsible for 70% of invasive cancers and precancerous lesions in the world.
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