An American study has shown that women who do not have the cervical cancer jab can see their risk of developing the disease half thanks to ‘herd immunisation’ if enough others do have it.
The findings, from a team at the The Cincinnati Children’s Hospital Medical Centre, found a substantial reduction in cases of human papilloma virus in vaccinated and unvaccinated teenagers
In 2006 and 2007, Dr Kahn and colleagues at Cincinnati Children’s recruited 368 young women between the ages of 13 and 16. The young women had sexual contact but none were vaccinated. In 2009 and 2010, they recruited a different group of 409 young women in the same age range, more than half of whom had received at least one dose of the vaccine.
The researchers compared pre- and post-vaccination HPV prevalence rates. The prevalence of vaccine-type HPV decreased 58 per cent overall, from 31.7 per cent to 13.4 per cent.
There was a 69 per cent decrease among vaccinated participants but also a 49 per cent drop in the unvaccinated.
Dr Jessica Kahn, a physician in the division of Adolescent Medicine at Cincinnati Children’s and lead author of the study, said: “Infection with the types of HPV targeted by the vaccine decreased in vaccinated young women by 69 per cent.
“Two of these HPV types, HPV-16 and HPV-18, cause about 70 per cent of cervical cancer. Thus, the results are promising in that they suggest that vaccine introduction could substantially reduce rates of cervical cancer in this community in the future.”
Dr Kahn emphasises that despite the evidence of herd immunity demonstrated in her study, vaccination of all young women between the ages of 11 and 26 is important to maximise the health benefits of vaccination.