Monitoring changes in non vaccine HPV types following the introduction of HPV vaccination is important to provide information on cross-protection and potential type-replacement.
We conducted a systematic review and meta-analysis to consider changes in the prevalence of non-vaccine HPV types in other studies comparing type-specific HPV prevalence between pre-vaccination and post-vaccination periods. Results were stratified by age-group (≤19 years old and 20-24 years old).
The meta-analysis included data from 9 studies. There was evidence of a decrease in HPV31 in the younger age-group (≤19 years old) but little evidence of a reduction in HPV33 or HPV45. Results were heterogeneous for HPV31, HPV33 and HPV45 in 20-24 year old women. There was some evidence of increases in some high-risk HPV types although these results were inconsistent for the two age-groups and the vaccine used.
We found evidence of cross-protection against some closely-related types. However, there was no clear evidence of type replacement; increases in non vaccine types could be due to other factors such as changes in study populations or an unmasking effect of broad spectrum assays. Continued monitoring of these HPV genotypes remains important. This presentation will also summarise more recent data on changes in non-vaccine HPV types following the introduction of HPV vaccination.