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Evidence review finds HPV vaccines to be safe, extremely effective
Liz Szabo, MA
Today at 9:00 a.m.
Human Papillomavirus (HPV)
Vaccine Integrity Project Twenty years after the approval of vaccines that prevent infection with the cancer-causing human papillomavirus (HPV), data continue to find that the shots are safe and extremely effective.
HPV vaccines reduce the risk of cervical cancer by 80% in women vaccinated by age 16 years and 66% in those vaccinated after 16, and aren’t associated with serious side effects, according to an evidence review published today by the Vaccine Integrity Project (VIP), an initiative of the University of Minnesota’s Center for Infectious Disease Research and Policy (CIDRAP), which publishes CIDRAP News.
HPV, which spreads through intimate contact, causes 90% of tumors of the cervix, as well as most cancers of the vagina, vulva, penis, anus, and the middle part of the throat.
About 50,000 people in the United States are diagnosed with an HPV-related cancer annually.
“The data show how important HPV vaccination is to prevent persistent HPV infections that lead to cancer,” said Angela Ulrich, PhD, MPH, CIDRAP’s director of research who led the evidence review.
HPV vaccines provide long-term benefits
Ongoing research has found that the benefits of HPV vaccines are even greater than recognized when they were first approved in June 2006, said Kevin Ault, MD, a professor of obstetrics and gynecology at the Western Michigan University Homer Stryker School of Medicine.
Studies have found evidence of protection against HPV up to 16 years after vaccination, according to the VIP report, which built on two evidence reviews published in 2025 by Cochrane, a global non-profit that publishes systematic reviews of healthcare interventions. The new report includes research published as recently as January.
“The duration of protection is long,” Ulrich said. “We have people who are 20, 30, 40 years old who are seeing protection from the HPV vaccine.”
About 80% of sexually active adults are infected with HPV at some point, often during their first sexual experience. In most cases, the immune system controls the virus and HPV causes no harm. But about 1% of those exposed to HPV develop chronic infections that can lead to cancer. There are nearly 13 million new infections each year.
A growing number of studies suggest that HPV vaccines prevent cancers outside the cervix. A study published in December 2025 found that women who received at least one dose of HPV vaccine were 37% less likely to develop precancerous lesions in the vagina or on the vulva than unvaccinated women.
We have people who are 20, 30, 40 years old who are seeing protection from the HPV vaccine.
And while HPV vaccines were primarily developed to prevent cervical cancer, studies suggest they protect both vaccinated and unvaccinated people from oral HPV infections, which can lead to cancer of the mouth, throat, and tonsils.
Experts say that HPV vaccination could prove to be even more of a game changer in oral and throat cancers than in cervical cancer, because there’s no way to screen for these malignancies, which are often diagnosed at later stages, when they are more difficult to cure.
In 2018, the Centers for Disease Control and Prevention (CDC) published data showing that oral and throat cancer had become the most common HPV-related malignancy.
Early data suggest that HPV vaccines are preventing these cancers, as well.
Men and boys who received the HPV vaccine from ages nine to 26 were nearly 50% less likely to develop cancers of the head and neck, esophagus, anus, or penis, according to a study published last month in JAMA Oncology.
Creating herd immunity
HPV vaccines even protect unvaccinated people, research suggests.
By dramatically reducing the amount of HPV in circulation, the vaccines have made it less likely for anyone—vaccinated or not—to be exposed to the virus during sex.
Declining rates of HPV infection, cervical precancers, and genital warts in unvaccinated people suggest that the vaccines have created “herd immunity,” which occurs when viral levels fall across a population, Ault said.
The first HPV vaccine, Merck’s Gardasil, was designed to prevent infection with four viral strains, including two strains of the virus that together cause most cervical cancers, as well as two strains that cause genital warts. Merck has updated the shot to protect against nine viral strains, including two that cause genital warts and seven that cause cancer.
Although the American Academy of Pediatrics (AAP) recommends that boys and girls begin HPV vaccination from age 9 to 12—when the shots have been shown to be most effective—Gardasil is approved for people up to age 45.
Filling a gap in data
Until last year, evidence reviews related to vaccination typically were performed by the CDC. An influential CDC advisory panel, the Advisory Committee on Immunization Practices (ACIP), met a little over one year ago to discuss the possibility of recommending a single dose of HPV vaccine.
Before the ACIP could propose any actions, however, Health and Human Services Secretary Robert F. Kennedy Jr. fired all 17 of its members. He then handpicked their replacements, many of whom have expressed anti-vaccine views. Last year, the new panel announced it would conduct a probe into the HPV vaccine’s safety.
In January, the CDC director slashed the number of recommended childhood vaccines from 17 to 11. As part of that overhaul, the CDC recommended a single HPV vaccine dose for girls and boys.
Many doctors criticized the change, because the CDC offered no scientific reason to support recommending only one dose.
To many people, the CDC’s decision seemed arbitrary, Ulrich said, because it was made “without transparency around those deliberations and knowing what the evidence says.”
Both parents and healthcare providers “were left wondering what to do,” said Noel T. Brewer, PhD, a professor of public health at the University of North Carolina, a member of an AAP committee reviewing HPV vaccination.
In March, a federal judge considering a lawsuit filed by the AAP, which claims the Trump administration’s vaccine policy changes were unlawful, wrote that several members of the ACIP “appeared distinctly unqualified,” and that the CDC’s changes to vaccination policy failed to follow legal requirements. The judge blocked Trump administration’s vaccine schedule changes, effectively restoring previous vaccination guidance.
Many doctors and public health advocates say they no longer trust the CDC or ACIP on science.
“The ACIP has lost their authority in the matter because of the extent to which they turned away from science and a rigorous process,” said Brewer, who was not involved in the new report.
More than half of states now follow vaccine recommendations from the AAP, which have not changed, rather than the CDC. CIDRAP has “taken over a function that that CDC used provide, that kind of timely literature review,” Brewer said.
Reassuring safety data
Medical societies had asked the VIP to rigorously review the safety of HPV vaccines, Ulrich said.
“They asked, ‘What additional information is there about safety? Are there any safety concerns, any red flags that are popping up in the literature that we need to be aware of?’” Ulrich said. “The answer is no. We did not find anything that was concerning or inconsistent with what has previously been found.”
This evidence represents hope—and a call to action to ensure more young people are protected.”
Like any shot, the HPV vaccine can cause pain at the injection site. But the VIP report, which includes 274 studies, found no evidence of increased risk of serious vaccine-related medical problems, such as neurological conditions, pregnancy complications, or other long-term health risks.
The VIP report’s findings stand in stark contrast to uclaims by Kennedy—who has made millions of dollars working with law firms suing Gardasil’s manufacturer—that HPV vaccines are unsafe.
The systematic review and meta-analysis screened more than 5,000 abstracts and evaluated more than 120 studies published from September 2024 to January 26, building on 153 studies in the two Cochrane reports. Evidence considered in the report included randomized controlled trials, cohort studies, ecological studies, case-control studies, and immunogenicity analyses.
Tamika Felder, who survived cervical cancer when she was 25, called the VIP report good news.
“This kind of independent review is exactly what we need in this moment," said Felder, now 50, who founded a support group called Cervivor after she finished cancer treatment. "It cuts through uncertainty and reaffirms that the HPV vaccine is both safe and highly effective at preventing cancer. This evidence represents hope—and a call to action to ensure more young people are protected.”
Questions about single-dose remain unanswered
Ulrich said the report addresses a lingering question: Can fewer doses of HPV vaccine work as well as the multiple doses now routinely given to children at ages 11 or 12?
The answer is nuanced, researchers said.
After analyzing a number of studies, the report concludes that a single dose vaccine “may offer comparable protection” against chronic HPV infection and cervical precancers for at least five years.
But the report notes there’s not yet enough evidence to answer other key questions: Does a single dose protect against cervical cancer for more than five years? Does one dose work as well as multiple doses to prevent cancers outside the cervix? And does a single dose fully protect boys?
The VIP’s “rigorous” review provides “very important data for those professional societies who are now deliberating on what updates to the current recommendations may be warranted,” said James Campbell, MD, vice chair of AAP’s committee on infectious diseases.
The AAP committee considering possible changes to HPV recommendations “is indebted to VIP for carefully and methodically presenting their findings," Campbell said.
Evidence review finds HPV vaccines to be safe, extremely effective
Liz Szabo, MA
Today at 9:00 a.m.
Human Papillomavirus (HPV)
Vaccine Integrity Project Twenty years after the approval of vaccines that prevent infection with the cancer-causing human papillomavirus (HPV), data continue to find that the shots are safe and extremely effective.
HPV vaccines reduce the risk of cervical cancer by 80% in women vaccinated by age 16 years and 66% in those vaccinated after 16, and aren’t associated with serious side effects, according to an evidence review published today by the Vaccine Integrity Project (VIP), an initiative of the University of Minnesota’s Center for Infectious Disease Research and Policy (CIDRAP), which publishes CIDRAP News.
HPV, which spreads through intimate contact, causes 90% of tumors of the cervix, as well as most cancers of the vagina, vulva, penis, anus, and the middle part of the throat.
About 50,000 people in the United States are diagnosed with an HPV-related cancer annually.
“The data show how important HPV vaccination is to prevent persistent HPV infections that lead to cancer,” said Angela Ulrich, PhD, MPH, CIDRAP’s director of research who led the evidence review.
HPV vaccines provide long-term benefits
Ongoing research has found that the benefits of HPV vaccines are even greater than recognized when they were first approved in June 2006, said Kevin Ault, MD, a professor of obstetrics and gynecology at the Western Michigan University Homer Stryker School of Medicine.
Studies have found evidence of protection against HPV up to 16 years after vaccination, according to the VIP report, which built on two evidence reviews published in 2025 by Cochrane, a global non-profit that publishes systematic reviews of healthcare interventions. The new report includes research published as recently as January.
“The duration of protection is long,” Ulrich said. “We have people who are 20, 30, 40 years old who are seeing protection from the HPV vaccine.”
About 80% of sexually active adults are infected with HPV at some point, often during their first sexual experience. In most cases, the immune system controls the virus and HPV causes no harm. But about 1% of those exposed to HPV develop chronic infections that can lead to cancer. There are nearly 13 million new infections each year.
A growing number of studies suggest that HPV vaccines prevent cancers outside the cervix. A study published in December 2025 found that women who received at least one dose of HPV vaccine were 37% less likely to develop precancerous lesions in the vagina or on the vulva than unvaccinated women.
We have people who are 20, 30, 40 years old who are seeing protection from the HPV vaccine.
And while HPV vaccines were primarily developed to prevent cervical cancer, studies suggest they protect both vaccinated and unvaccinated people from oral HPV infections, which can lead to cancer of the mouth, throat, and tonsils.
Experts say that HPV vaccination could prove to be even more of a game changer in oral and throat cancers than in cervical cancer, because there’s no way to screen for these malignancies, which are often diagnosed at later stages, when they are more difficult to cure.
In 2018, the Centers for Disease Control and Prevention (CDC) published data showing that oral and throat cancer had become the most common HPV-related malignancy.
Early data suggest that HPV vaccines are preventing these cancers, as well.
Men and boys who received the HPV vaccine from ages nine to 26 were nearly 50% less likely to develop cancers of the head and neck, esophagus, anus, or penis, according to a study published last month in JAMA Oncology.
Creating herd immunity
HPV vaccines even protect unvaccinated people, research suggests.
By dramatically reducing the amount of HPV in circulation, the vaccines have made it less likely for anyone—vaccinated or not—to be exposed to the virus during sex.
Declining rates of HPV infection, cervical precancers, and genital warts in unvaccinated people suggest that the vaccines have created “herd immunity,” which occurs when viral levels fall across a population, Ault said.
The first HPV vaccine, Merck’s Gardasil, was designed to prevent infection with four viral strains, including two strains of the virus that together cause most cervical cancers, as well as two strains that cause genital warts. Merck has updated the shot to protect against nine viral strains, including two that cause genital warts and seven that cause cancer.
Although the American Academy of Pediatrics (AAP) recommends that boys and girls begin HPV vaccination from age 9 to 12—when the shots have been shown to be most effective—Gardasil is approved for people up to age 45.
Filling a gap in data
Until last year, evidence reviews related to vaccination typically were performed by the CDC. An influential CDC advisory panel, the Advisory Committee on Immunization Practices (ACIP), met a little over one year ago to discuss the possibility of recommending a single dose of HPV vaccine.
Before the ACIP could propose any actions, however, Health and Human Services Secretary Robert F. Kennedy Jr. fired all 17 of its members. He then handpicked their replacements, many of whom have expressed anti-vaccine views. Last year, the new panel announced it would conduct a probe into the HPV vaccine’s safety.
In January, the CDC director slashed the number of recommended childhood vaccines from 17 to 11. As part of that overhaul, the CDC recommended a single HPV vaccine dose for girls and boys.
Many doctors criticized the change, because the CDC offered no scientific reason to support recommending only one dose.
To many people, the CDC’s decision seemed arbitrary, Ulrich said, because it was made “without transparency around those deliberations and knowing what the evidence says.”
Both parents and healthcare providers “were left wondering what to do,” said Noel T. Brewer, PhD, a professor of public health at the University of North Carolina, a member of an AAP committee reviewing HPV vaccination.
In March, a federal judge considering a lawsuit filed by the AAP, which claims the Trump administration’s vaccine policy changes were unlawful, wrote that several members of the ACIP “appeared distinctly unqualified,” and that the CDC’s changes to vaccination policy failed to follow legal requirements. The judge blocked Trump administration’s vaccine schedule changes, effectively restoring previous vaccination guidance.
Many doctors and public health advocates say they no longer trust the CDC or ACIP on science.
“The ACIP has lost their authority in the matter because of the extent to which they turned away from science and a rigorous process,” said Brewer, who was not involved in the new report.
More than half of states now follow vaccine recommendations from the AAP, which have not changed, rather than the CDC. CIDRAP has “taken over a function that that CDC used provide, that kind of timely literature review,” Brewer said.
Reassuring safety data
Medical societies had asked the VIP to rigorously review the safety of HPV vaccines, Ulrich said.
“They asked, ‘What additional information is there about safety? Are there any safety concerns, any red flags that are popping up in the literature that we need to be aware of?’” Ulrich said. “The answer is no. We did not find anything that was concerning or inconsistent with what has previously been found.”
This evidence represents hope—and a call to action to ensure more young people are protected.”
Like any shot, the HPV vaccine can cause pain at the injection site. But the VIP report, which includes 274 studies, found no evidence of increased risk of serious vaccine-related medical problems, such as neurological conditions, pregnancy complications, or other long-term health risks.
The VIP report’s findings stand in stark contrast to uclaims by Kennedy—who has made millions of dollars working with law firms suing Gardasil’s manufacturer—that HPV vaccines are unsafe.
The systematic review and meta-analysis screened more than 5,000 abstracts and evaluated more than 120 studies published from September 2024 to January 26, building on 153 studies in the two Cochrane reports. Evidence considered in the report included randomized controlled trials, cohort studies, ecological studies, case-control studies, and immunogenicity analyses.
Tamika Felder, who survived cervical cancer when she was 25, called the VIP report good news.
“This kind of independent review is exactly what we need in this moment," said Felder, now 50, who founded a support group called Cervivor after she finished cancer treatment. "It cuts through uncertainty and reaffirms that the HPV vaccine is both safe and highly effective at preventing cancer. This evidence represents hope—and a call to action to ensure more young people are protected.”
Questions about single-dose remain unanswered
Ulrich said the report addresses a lingering question: Can fewer doses of HPV vaccine work as well as the multiple doses now routinely given to children at ages 11 or 12?
The answer is nuanced, researchers said.
After analyzing a number of studies, the report concludes that a single dose vaccine “may offer comparable protection” against chronic HPV infection and cervical precancers for at least five years.
But the report notes there’s not yet enough evidence to answer other key questions: Does a single dose protect against cervical cancer for more than five years? Does one dose work as well as multiple doses to prevent cancers outside the cervix? And does a single dose fully protect boys?
The VIP’s “rigorous” review provides “very important data for those professional societies who are now deliberating on what updates to the current recommendations may be warranted,” said James Campbell, MD, vice chair of AAP’s committee on infectious diseases.
The AAP committee considering possible changes to HPV recommendations “is indebted to VIP for carefully and methodically presenting their findings," Campbell said.