HPV prevalence peaks in 14- to 19-year-old women

OB/GYN News, June 1, 2006 by Damian McNamara

JACKSONVILLE, FLA. -- The prevalence of high-risk human papillomavirus in U.S. women is highest in the 14- to 19-year-old age group, according to a presentation at an STD prevention conference sponsored by the Centers for Disease Control and Prevention.

One HPV vaccine is expected to debut this summer and another before the end of the year, but the exact age group for which the vaccines will be recommended has not yet been determined.

"For the vaccine to have an optimal effect, it should be given before initiation of sexual behavior. A routine universal vaccination of 11- to 12-year-old females is under consideration," said Cristen Suhr, project coordinator of the HPV sentinel surveillance project sponsored by the CDC.

High-risk human papillomavirus (HR-HPV) is defined as HPV 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, and/or 68 in the HPV surveillance project.

An overall HR-HPV prevalence of 22%--regardless of race or age group--is among the findings of the HPV sentinel surveillance project. The prevalence of HR-HPV in 14- to 19-year-olds is 33%. The project is the first multisite surveillance to measure HR-HPV prevalence among U.S. women.

Researchers assessed 8,426 females aged 14-65 years old. Participants had a routine Pap smear between January 2003 and December 2005 in one of six cities: Baltimore, Boston, Denver, Los Angeles, New Orleans, or Seattle. Medical records were later abstracted for results.

Although nearly 60% of participants fell into the two youngest age groups (14- to 19-year-olds and 20- to 29-year-olds), "a strength of the ongoing HPV sentinel surveillance is inclusion of older age groups," said Ms. Suhr. "Older women were more likely to be enrolled through a primary care clinic, whereas younger women were more likely to be enrolled through a family planning or STD clinic.

"There was a steady decline in prevalence as age increased, from more than 30% in 14- to 19-year-olds down to under 10% in 50- to 65-year-olds," Ms. Suhr said. This higher prevalence among younger females supports other studies that suggest HPV infection is acquired shortly after initiation of sexual activity. Ms. Suhr is affiliated with the CDC's division of STD prevention and with Business Computer Applications Inc. in Atlanta.

HPV is the most common sexually transmitted infection, with a prevalence estimated at 20 million cases in the United States. Approximately 5.5 million incident infections occur each year. The HPV family is large, with more than 100 viral types, including more than 40 that cause genital infections. Most new infections are asymptomatic and clear naturally.

Licensure of the quadrivalent vaccine Gardasil (Merck & Co.) is imminent, according to multiple experts at the meeting. The vaccine targets high-risk oncogenic virus types 16 and 18, implicated in 70% of cervical cancers, as well as low-risk, nononcogenic types 6 and 11, which cause 90% of genital warts. Licensure of an investigational HPV bivalent vaccine, Cervarix (GlaxoSmithKline), is expected as early as the end of 2006.

"In the U.S., it appears we will be able to reduce abnormal Pap smears with the vaccines," Dr. Diane M. Harper said. "We know the vaccines are safe [and] immunogenic and can prevent HPV infections--incident and persistent--and prevent genital warts." Dr. Harper is director of the Gynecologic Cancer Prevention Research Group at the Norris Cotton Cancer Center in Lebanon, N.H.

Potential limitations of the study include its clinic-based population and use of noncentralized laboratories for testing of cervical fluid samples.

Prevalence of High-Risk HPV, by Age
(n = 8,426)

14-19  33%
20-29  28%
30-39  14%
40-49  11%
50-65   6%

Source: Ms. Suhr

Note: Table made from bar graph.

BY DAMIAN MCNAMARA

Miami Bureau