A sharp drop in the number of young women infected with the two strains of human papillomavirus (HPV) most likely to cause cervical cancer occurred in England after the 2008 launch of a national vaccination programme there, a new study shows.
The high-risk HPV types 16 and 18 cause 70% to 80% of cervical cancers. Protection against infection from these two types is included in HPV vaccines.
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The British researchers analysed test results from more than 4000 young women between 2010 and 2012. Before the start of the HPV vaccination programme, about one in five sexually active women aged 16 to 18 had at least one of the two high-risk HPV types. That dropped to one in 15 after the vaccination programme began.
The investigators also found that this age group had the highest rate of infection with the two high-risk HPV strains before the start of the immunisation programme, but had the highest vaccination rate and lowest infection rate once the programme began.
The study is to be presented at the Society for General Microbiology annual conference in Liverpool, England. Research presented at meetings should be considered preliminary until published in a peer-reviewed medical journal.
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"This study provides an early indication that the national HPV immunisation programme is successfully reducing vaccine-type HPV infections in sexually active young women in England, and also suggests herd immunity may be benefiting non-vaccinated young women and men," David Mesher, of Public Health England, said in a society news release.
Herd immunity happens when vaccination of a large portion of a population affords some protection against infection to those in the population who are not vaccinated.
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