Change in population prevalences of human papillomavirus after initiation of vaccination: the high-throughput HPV monitoring study.

BACKGROUND: Organized human papillomavirus (HPV) vaccination was introduced in Sweden in 2012. On-demand vaccination was in effect from 2006 to 2011. We followed the HPV prevalences in Southern Sweden from 2008 to 2013.
METHODS: Consecutive, anonymized samples from the Chlamydia trachomatis screening were analyzed for HPV DNA for two low-risk types and 14 high-risk types using PCR with genotyping using mass spectrometry. We analyzed 44,146 samples in 2008, 5,224 in 2012, and 5,815 in 2013.
RESULTS: Registry-determined HPV vaccination coverages of the population in Southern Sweden increased mainly among 13- to 22-year-old women. Most analyzed samples contained genital swabs from women and the HPV6 prevalence in these samples decreased from 7.0% in 2008 to 4.2% in 2013 [-40.0%; P < 0.0005 (χ(2) test)]. HPV16 decreased from 14.9% to 8.7% (-41.6%; P < 0.0005) and HPV18 decreased from 7.9% to 4.3% (-45.6%; P < 0.0005) among 13- to 22-year-old women. There were only small changes in vaccination coverage among 23- to 40-year-old women. In this age group, HPV18 decreased marginally (-19.6%; P = 0.04) and there were no significant changes for HPV6 or HPV16. Two nonvaccine HPV types (HPV52 and HPV56) were increased among 13- to 22-year-old women, both in 2012 and 2013.
CONCLUSIONS: A major reduction of HPV6, 16, and 18 prevalences is seen in the age groups with a concomitant increase in HPV vaccination coverage. The minor changes seen for nonvaccine types will require further investigation. IMPACT: Monitoring of type-specific HPV prevalences may detect early effects of HPV vaccination. ©2014 American Association for Cancer Research.