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HPV Vaccine Protecting Against Infections, Even Among Unvaccinated
- October 1, 2025
- Dennis Thompson HealthDay Reporter
The human papillomavirus (HPV) vaccine is protecting women from the cervical-cancer-causing virus — including those who don’t get the jab, a new study says.
Depending on which vaccine they received, HPV infections fell by 76% to 98% over 17 years among vaccinated women, researchers reported in the journal JAMA Pediatrics.
But infections also fell by 72% to 76% among unvaccinated women during the same period, results showed.
“There are two encouraging takeaways from our study,” said senior researcher Dr. Jessica Kahn, chair of head and neck pathology at the Albert Einstein College of Medicine in New York City.
“First, HPV vaccines work remarkably well in a real-world setting, even among women at high risk for HPV and who may not have received all vaccine doses,” she said in a news release. “Second, we saw clear evidence of herd immunity, meaning when enough people are vaccinated, the vaccine indirectly protects unvaccinated people by reducing overall virus transmission.”
Kahn said these results "reinforce the potential of the HPV vaccine to prevent infection and, ultimately, eliminate cervical cancer globally.”
Long-lasting infection with high-risk strains of HPV causes virtually all cervical cancers, according to the National Cancer Institute. It’s also responsible for other genital cancers and head and neck cancers in both women and men.
In the United States, three HPV vaccines have been approved, researchers said in background notes.
The first vaccines, approved in 2006, protects against four strains, HPV-6, HPV-11, HPV-16 and HPV-18. Another, approved in 2009, protects against two high-risk strains, HPV-16 and HPV-18. The third, approved in 2014, is effective against nine different strains, including all of the strains in the first two vaccines.
The nine-strain vaccine is the only one available in the U.S. since 2016, and it targets HPV strains responsible for about 90% of cervical cancers, researchers said.
For the new study, researchers tracked HPV infections among more than 2,300 young women in Cincinnati between October 2006 and September 2023. About 79% had two or more male sexual partners, increasing their risk of HPV, and 51% had a history of at least one sexually transmitted infection (STI).
During the study period, HVP vaccination rates reached as high as 82% among the women, researchers found.
As vaccination coverage increased, HPV infections dropped dramatically:
98% among women who got the 2-valent vaccine.
94% for women covered by the 4-valent vaccine.
76% among women who received the 9-valent vaccine.
“Our analysis of the data indicates that those reductions in infection rates were primarily due to the vaccine’s introduction and not because of changes in sexual behavior or other factors,” lead researcher Aislinn DeSieghardt said in a news release. She’s a clinical research coordinator at Cincinnati Children’s Hospital Medical Center.
Further, the data showed that herd immunity protected even women who were not vaccinated.
Infections among the HPV types covered by the 2-valent vaccine fell by nearly 72% among the unvaccinated, and infections of the types covered by the 4-valent vaccine fell by 76%, the study found.
Kahn said this herd immunity was likely related to robust vaccination rates among boys as well as girls. However, she noted there’s not yet enough data to confirm that the 9-valent vaccine provides similar herd protection.
“In the United States and other countries with widespread HPV vaccination programs, cervical cancer rates are already declining,” Kahn said.
“By expanding uptake of this highly safe and effective vaccine, and ensuring access to screening and treatment, we can achieve one of the greatest public health victories of our time: the elimination of cervical cancer worldwide,” she concluded.
More information
The National Cancer Institute has more on cervical cancer.
SOURCES: Albert Einstein College of Medicine, news release, Sept. 29, 2025, JAMA Pediatrics, Sept. 29, 2025
