More than 20 million people are currently infected with the virus, and 6.2 million new infections are diagnosed each year. Most HPV infections are cleared by the immune system, but some persist, causing pre-cancerous lesions known as CIN2/3 and, ultimately, cervical cancer. Half of the more than 30 known sexually transmitted strains of HPV are considered high-risk types linked to cervical cancer.
The vaccine GARDASIL™ was licensed for females nine-to-26 years old to prevent HPV-related cervical cancer, cervical, vaginal, and vulvar cancer precursors, and anogenital warts. The vaccine targets the strains HPV16 and HPV18 that are thought to cause 70 percent of cervical cancers. It also targets strains HPV6 and HPV11 that cause 90 percent of genital warts.
To monitor the early impact of the HPV vaccine, the Yale office of the Connecticut Emerging Infections Program will survey pathology laboratories and health care providers for information about new CIN2/3 diagnoses among women in New Haven County. The goal is to determine whether there has been a decrease of new diagnoses since the introduction of the vaccine.
"We expect to see the greatest impact among young women, but over time we also expect to see effects for women over 26 who were vaccinated at a younger age," said Linda Niccolai, assistant professor and director of the project under the emerging infections program Niccolai said. "Also, there will presumably be less transmission to male partners, who can re-infect their partners."
Niccolai notes that if it can be shown there are fewer pre-cancerous lesions due to vaccination, the vaccine might be made more widely available.
"Perhaps structural and financial policy changes also will be made to increase accessibility for those who want the vaccine," said Niccolai.
This work is supported by the Centers for Disease Control and Prevention (CDC) in Atlanta, Ga. The CDC, which reports 9,710 new cases of cervical cancer each year leading to some 3,700 deaths, has selected four monitoring sites in four states—California, New York, Tennesee, and Connecticut.
James Meek, associate director of the emerging infections program, said another goal is to watch for possible changes in the strain of the virus responsible for the pre-cancerous lesions.
"As vaccine use increases, we expect to see a decrease in the occurrence of lesions caused by HPV strains 16 or 18," he said. "It will be important to know if other less common cancer-causing strains of HPV, such as HPV33 or HPV45, become more common."
Source: YALE University