We undertook initially the first study which was conducted throughout 2009 and it was looking at the HPV genotypes that were present within the cervical smears that had been taken of women of screening age in Northern Ireland, so at that time it was women between the ages of 20 and 64. Within that study what we identified was that around a third of women in the age group of 20-24 years had a high risk human papilloma virus present within their cervical sample. The rate of high risk HPV decreased with increasing age which is consistent with the literature which suggests that some HPV types remain prevalent in certain women and others regress.
So within the first study we looked at 6,000 women and within those we identified 13% overall that had high risk human papilloma virus. We also conducted a systematic review of the literature looking across the UK at other studies and our results fitted in fairly well with the other studies across the United Kingdom. The main type that we found within the cervical samples was HPV16 which the current vaccination programme covers. We also found other high risk HPV genotypes including 52, 59, 31 and others and HPV18 was present but in a smaller proportion of women within Northern Ireland.
The implication of it is that there are a large number of women within the population that do have high risk human papilloma virus. We also then looked in the second study at women who had cervical disease, that was right through from cervical intraepithelial neoplasia 1 through to cervical cancer. In those types we found HPV16 was the most common type in women who developed cervical cancer but we also identified HPV52, 45, 35 and 18 as being implicated in cervical cancer within Northern Ireland.
So the current vaccination programme covers the majority of types of HPV that are implicated in the development of cervical disease, however, there are other HPV types that aren’t within the vaccine that it does not cover. So it is therefore important that women, including those who have been vaccinated and also those who are not vaccinated, if they’re invited to go for a cervical smear that they attend.
Do we need another vaccine?
Yes, at the minute there are a number of companies that are undertaking to try and develop polyvalent vaccines, so vaccines that cover additional types on top of the four that are currently covered in the current vaccine and that these may be region specific, so there do appear to be differences between the UK and elsewhere in the world. So this information that we’ve collected as part of this study and other studies within the UK will be really important in trying to determine which HPV vaccination type we should use.