According to a recent report by the U.S. Centers for Disease Control and Prevention, there has been a major drop in cervical precancers in young women since the human papillomavirus (HPV) vaccine was introduced nearly two decades ago. Public health officials say the decline is clear evidence of the vaccine’s effectiveness in preventing disease.

HPV is the most common sexually transmitted infection and a major cause of certain cancers, including cervical cancer in women. It is estimated that there are 13 million new HPV infections every year in the U.S. The HPV vaccine is considered the most cost-effective public health measure against cervical cancer.

Cervical precancers are abnormal cells or tissues that have a risk of developing into cervical cancer if left untreated. They have been used to monitor the early impacts of the HPV vaccine due to their short developmental stages and greater numbers relative to cervical cancer.

The Yale School of Public Health (YSPH) is one of five sites in the United States that collects data on cervical precancers to determine the efficacy of the HPV vaccine. The YSPH monitoring program is part of a larger, national CDC initiative known as the Human Papillomavirus Vaccine Impact Monitoring Project or HPV-IMPACT.

Monica Brackney, MS, an epidemiologist with YSPH’s Emerging Infections Program, is project manager of CT HPV-IMPACT. She recently discussed the potential implications of the CDC cervical cancer report and what individuals can do to reduce their risk of HPV.

What did the CDC report say about a decline in cervical precancers?

Monica Brackney (MB): According to a CDC Morbidity and Mortality Weekly Report (MMWR) issued last February, the collected data shows that from 2008 to 2022, cervical precancers decreased by 80% among women aged 20-24 who were screened for cervical cancer. This is the age group that was most likely to be vaccinated for HPV. The vaccine was approved for use by the FDA in 2006 and it was recommended for girls age 11-12. Women in the oldest age groups (40-49, 50-64 years) saw no decrease in cervical precancers. These women were never eligible to be vaccinated at the recommended age or for catch-up vaccination.

How did YSPH and the CT Emerging Infections Program (EIP) contribute to the CDC report?

MB: The CDC report included data from 5 Emerging Infections Program (EIP) HPV-IMPACT sites including the CT HPV-IMPACT site here at YSPH. The CT EIP is a partnership between CT Department of Public Health and YSPH and began in 1995. There are currently 12 sites across the country. The CT EIP HPV-IMPACT project began at YSPH in 2007 to assess the early impact of the HPV vaccine. To do this, we collect data on all cervical precancers detected in women living in New Haven County. This work takes close collaboration with state health department partners, hospital and commercial pathology laboratories and doctors across the state. Yale EIP staff follow up on each precancer case by reviewing the medical record and often calling the woman with the cervical precancer. All of this data is then gathered, cleaned and verified by EIP staff and students at YSPH and shared with CDC, where it is combined with data from the other 4 sites. Fifteen years of this combined data were reviewed by CDC and the HPV-IMPACT program sites for this report.

What can people do to reduce their risk of HPV?

MB: The HPV vaccine is an exceptionally effective vaccine and it is the best method for preventing HPV infection. The current vaccine protects against the seven most common types of HPV that cause cancer and the two most common types of HPV that cause genital warts. Clinical trials have demonstrated nearly 100% efficacy in preventing these types of HPV infection, cervical precancers, and genital warts. In addition, the vaccine has been found to be highly effective against anal precancers in men who have sex with men. Regular cervical cancer screening is also important to prevent HPV-related cervical cancer, especially for those who were not vaccinated before their first potential HPV exposure.

The HPV vaccine is currently recommended for all children ages 11-12 to generate immunity to HPV, with catch-up vaccination through age 26.