By Cara Murez HealthDay Reporter
MONDAY, Aug. 22, 2022 (HealthDay News) — In 2006, doctors began recommending the first sexually transmitted human papillomavirus (HPV) vaccine, with vaccines having the potential to reduce the risk of certain cancers.
Now a new study shows the vaccine was extremely effective, nearly eliminating the prevalence of the two most dangerous strains of the virus among young women by 2016.
Crucially, it didn’t just benefit young women who received the HPV vaccine: it also provided herd immunity, with lower prevalence rates even among those who weren’t vaccinated because the virus has been prevented from circulating so widely.
“Before the introduction of the vaccine, the predicted probability of prevalence was quite high, 15%,” said study author Ashish Deshmukh, associate director of the Center for Health Services Research at the University of Texas Health School of Public. Health in Houston. “And after the introduction of the HPV vaccine, the prevalence dropped significantly, both in vaccinated and unvaccinated women. It conveys the impact of HPV vaccination.
Dr. Linda Eckert, a professor of obstetrics and gynecology at the University of Washington in Seattle, who was not involved in the study, said it was great news that HPV levels went down even in unvaccinated women.
“The impact on those vaccinated was also encouraging, showing stunning protection against the two most common types of HPV that cause cervical cancer,” Eckert said.
However, it could be even better, the researchers added.
The vaccine, which is available for girls and boys from age 9 and into young adulthood, is still not as widely used as experts would like. From 2015 to 2016, about 55% of American women aged 18 to 20 had received their vaccines, along with 52% of those aged 21 to 23 and 50% of those aged 24 to 26, according to the study. .
“In the US, we still don’t have optimal coverage,” Deshmukh said. “When we think about optimal coverage, the goal is to hit that 80% target.”
Despite suboptimal coverage, the results are very promising, he noted.
“On a broader level, we’re starting to see an impact and that provides a positive perspective on that. If we are able to improve coverage to an even higher level, we might even see greater elimination of HPV infection,” he added.
Reducing HPV infections is a big step toward reducing precancerous lesions and has the potential to reduce cancer incidence nationwide, Deshmukh said.
“We started to see a reduction in cancer incidence in a very young group of women. Thus, among those under the age of 25, cancer incidence rates have dropped significantly. And several studies have documented a reduction in the incidence of cervical cancer in very young women,” he explained.
The study focused on women aged 18 to 26 and found that the prevalence of the virus from 2005 to 2006 was 15.2%. Ten years later, this percentage had fallen to 3.3% overall for this age group, including 5.1% for those who were not vaccinated, 1% for the vaccinated groups and 0% among the vaccinated women at the younger end of the study cohort.
The estimated probability of HPV infection with strains 16 and 18, those considered most likely to trigger cancer, was 78% lower overall from 2015 to 2016 than from 2005 to 2006 – 60% lower for non vaccinated and 92% lower for the vaccinated, the investigators found.
Among the states with the lowest vaccination rates are those in the Midwest and Southeast, and the incidence of HPV-associated cancer remains high in those states, Deshmukh said.
The reasons for not getting vaccinated are largely driven by unfounded safety concerns on the part of parents, he noted.
“There needs to be more awareness to inform and create understanding that vaccination is actually safe and effective,” Deshmukh said.
The stigma that getting vaccinated is somehow a license for sexual activity is not true and has hampered vaccination rates, Eckert noted.
With higher vaccine coverage, the United States could be like Australia, which rolled out the vaccine in 2007 and achieved much higher coverage.
“It’s significantly decreased, and they think they’re going to eliminate cervical cancer by 2035,” Eckert said.
Meanwhile, cervical cancer rates are rising globally because vaccine distribution is not equitable around the world. The World Health Organization estimates that around 90% of new cases and deaths worldwide in 2020 occurred in low- and middle-income countries.
HPV is an umbrella term for about 200 related viruses, according to the US National Cancer Institute. Some of them spread through sexual contact. Certain strains of the virus can cause cancer of the cervix, throat, mouth, vagina, vulva, anus and penis.
The United States Centers for Disease Control and Prevention recommends vaccination from age 11 or 12, although it is allowed in children as young as 9 years old. It is only available up to the age of 26, with some exceptions for people aged 27 to 45 after consultation with a doctor. The Gardasil-9 vaccine is distributed in the United States and it covers nine strains of HPV, including 16 and 18.
HPV 16 and 18 account for about 70% of cervical cancers, Eckert said.
She cautioned, however, that even vaccinated people should continue to get tested, as other types of HPV not targeted by the vaccine can also cause cancers or pre-cancerous cells.
“I don’t want to give the message that we’re free at home,” Eckert said. “It’s always very important to get tested.”
The United States Centers for Disease Control and Prevention has more on HPV vaccination.
SOURCES: Ashish Deshmukh, PhD, MPH, associate professor, management, policy, and community health and associate director, Center for Health Services Research, University of Texas Health School of Public Health, Houston; Linda Eckert, MD, assistant professor, global health, and professor, obstetrics and gynecology, University of Washington, Seattle; JAMA Health ForumAugust 19, 2022, online
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