An exciting paper about the success of the bivalent HPV (human papilloma virus) vaccine in preventing cervical cancer was published this week in The Lancet! It is out of England and contains observational data spanning 10 years. This paper is significant becuase it doesn’t just look at infection of HPV but actually evaluates the reduction of cervical cancer, the target clinical outcome. The second clinical readout of the paper is the rate of CIN3 (grade 3 cervical intraepithelial neoplasia).
What did it find?
▪️Young women who recieved the HPV vaccine between the years of 12 and 18 had a significantly reduced incidence rate of cervical cancer (34-87%).
▪️Younger vaccination (12-13 years) resulted in the greatest reduction in cervical cancer (87% reduction in cancer and 97% reduction in abnormal cervical screen).
▪️Secondarily, there appears to be a small benefit of inviting women to screen for cervical cancer younger (20 years compared to 25 years).
Importantly, this observational study is looking at the bivalent HPV vaccine (Cervarix) which covers HPV 16 and 18, the two strains that account for approximately 70% of cervical cancer cases. In the U.S., Gardasil is the approved vaccine for HPV. In 2006 the quadrivalent (4-strain) Gardasil vaccine was FDA approved (covers HPV 6, 11, 16, and 18) followed by a version that covers 9 strains (Gardasil9) in 2014. Data was published in the US earlier this year, showing a signficant decline in HPV infection prevalence (80-90%) with vaccination. There is also a published paper in the NEJM from early 2020 that reviewed cervical cancer prevalance in Sweden (using quadrivalent gardasil) which found that there was a nearly 90% reduction in young women vaccinated before age 17!
Future questions now surround the optimal number of doses. There is some evidence that suggests a vaccination series of 3 doses may not be required. More on that to come!
What’s the conclusion? Confirmation that the bivalent HPV vaccine also shows a reduction in cervical cancer is amazing! This should further motivate parents to vaccinate their children against HPV early.
UK Bivalent Data – The Lancet. Nov 2021.
US Gardasil Data – MMWR. Mar 2021. & re-aligned table.