The HPV vaccine may the reason behind the large decline in genital warts diagnoses in Australian women, a new study published on April 18 in BMJ reveals.
HPV or human papillomavirus is the most common sexually transmitted infection, but many people do not know they have it. There are more than 40 types of viruses that can infect the genital area of men and women, as well as many more than can attack the mouth and throat.
It is passed through genital contact, most often through vaginal and anal sex. It can be passed through oral sex and genital-to-genital contact, even if the infected has no symptoms at the time. In rare occasions, a mother can pass genital HPV to her baby during delivery.
While in 90 percent of the cases the person's body will clear HPV from its system within two years, it can develop into different health problems. Some HPV can cause genital warts in men and women or warts in the throat known as recurrent respiratory papillomatosis (RRP). It can also cause normal cells to turn into abnormal cancer cells over time. HPV has been known to cause cervical, vulva, vagina, penis, anus and oropharynx (back of the throat, including the base of the tongue and tonsils) cancers.
The Centers of Disease Control and Prevention recommend that girls and boys at age 11 or 12 get the HPV vaccine, as well as women through the age of 26 and men through the age of 21 who did not get the vaccine when they were younger. It is also recommended for gay men, bisexual men and any man who has sex with a man. People with compromised immune systems because of illnesses like HIV or AIDS are also recommended to get the vaccine through the age of 26 if they did not get it earlier.
Australia introduced a program to offer free HPV vaccinations to girls between the ages of 12 to 13 years old in 2007. Catch-up programs for girls and young women 13 to 18 year olds and 18 to 26 year olds were implemented from 2007 through 2009. The vaccine that was used is supposed to protect against the types of HPV that cause 90 percent of genital warts and the HPV that causes cancer.
Early information showed that two years after the program began, genital warts diagnoses went down 59 percent in women and 39 percent in heterosexual men. It also may have led to a decrease in high-grade cervical abnormalities.
To see any further effects, researchers looked at data from eight sexual health services across Australia.. The study subjects were then divided into the pre-vaccination period (2004-2007) and five years into the vaccination period (2007-2011). They were also broken up into those who were under 21, 21 to 30 year olds and those 30 and older.
Between 2004 and 2011, 85,770 patients were seen for the first time. Nine percent of them were diagnosed with genital warts. When further breaking down the data, Men's rates went from 13 percent in 2004 to 12 percent in 2007 and then decreased during the vaccination period to 7 percent, which meant they remained statistically stable.
Women's rates changed, however. It was shown that women diagnosed with genital warts went from 9 percent in 2004 to 10 percent in 2007, and then down to 3 percent during the vaccination period. In women under 21, 9 percent were diagnosed with genital warts in 2004 and 11 percent in 2007. But during the vaccination period, rates went down to 0.85 percent . No cases were diagnosed in 2011 among the women who were vaccinated in that age group. Among the women who weren't vaccinated under 21, the rate was 7 percent during that same year.
Significant declines in genital warts were also shown in women between 21 and 30 and heterosexual men under 21 and between the ages of 21 and 30, but no significant trends were seen in both women and heterosexual men over the age of 30.
"All indications are that the program has been an overwhelming success," study author Dr. Basil Donovan, who heads the sexual health program at the Kirby Institute of the University of New South Wales, in Sydney, said to HealthDay.
"But we won't be certain until HPV-related cancers [also] start dropping," he added, pointing out that "the incubation period from HPV infection to HPV-related cancer is typically at least 20 to 30 years."
Clinical Director Simon Barton and Sexual Health and HIV Consultant Colm O'Mahony, who both wrote an accompanying editorial, said the results were "worth celebrating the extraordinary success."
The two wrote that these are "exciting times in the science of HPV" and we can hopefully look forward to "virtual elimination of genital warts [...] most genital cancers and some 60% of head and neck cancers."
Donovan noted that there wasn't resistance to the vaccine in Austrailia, but in countries like the U.S. where there was a "fractured" response due to the controversy surrounding the proposal to vaccinate young girls. He believes that in countries that have accepted the vaccine, he expects rates to drop down as well.
Prince Edward Island in Canada announced on Friday that they would be expanding their HPV vaccine program to include boys in the sixth grade, which means they will be between the ages of 11 and 12. A program to vaccinate girls began in 2007.
"Boys can be the source of the virus for their female partners," Deputy chief public health officer Dr. Lamont Sweet to the CBC. "By preventing boys from carrying the virus, you in turn will prevent girls from getting the virus which causes cervical cancer."