Findings from the study, the first to measure the impact of the vaccine Gardisil since its arrival on the market in 2006, have impressed health experts. So much so that it has even impressed a US government official – who heralded the results a success for the immunisation campaign.
“This report shows that HPV works well, and the report should be a wake-up call to our nation to protect the next generation by increasing HPV vaccination rates,” said Dr Thomas Frieden, director of the US Centres for Disease Control and Prevention, in a statement.
Even those who haven’t received the vaccination are benefiting from the drop in number of infections circulating among US teens, the study, published in the Journal of Infectious Diseases, reported.
However, Dr Frieden pointed out that the vaccination rate was still low, with only a third of teenage girls aged 13-17 having been fully vaccinated with the HPV vaccines. This compares with much higher vaccination rates in countries like Rwanda – where 80 per cent of all teenage girls have received the vaccination.
“Our low vaccination rates represent 50,000 preventable tragedies – 50,000 girls alive today will develop cervical cancer over their lifetime that would have been prevented if we reach 80 percent vaccination rates,” Frieden pointed out.
Regardless of the low rates experts believe the higher than expected response to the vaccine could be the result of “herd-immunity” – the phenomenon of reducing infections amongst the unvaccinated. Or it could also mean the vaccine was effective in women who had been given one shot and not received the full three recommended doses.
The research team used data from a health survey compiled in the four-year period before the vaccine was introduced. They compared the rates of infection of certain strains of HPV amongst girls and women aged 14-19.
The proportion of infections was found to drop 56 per cent. The drop was higher amongst girls who received the vaccine – at 88 per cent.
There are four known strains of Human Papillomavirus known to cause cervical cancer and genital warts. HPV infections are though to be responsible for causing 19,000 cases of cancer each year for women in the US. The HPV infection is also harmful for men, with 8,000 cases of cancer a year reported in US men – of which throat cancer is the most common.