Two major Cochrane reviews provide the strongest evidence to date that HPV vaccines are highly effective at preventing cervical cancer and other HPV-related diseases—while posing no increased risk of the serious side effects that frequently circulate on social media. Together, the studies include data from more than 132 million people and offer renewed clarity at a moment when misinformation still discourages some families from vaccinating their children.
Nicholas Henschke, PhD, lead author of one review and contributor to another, and head of the Cochrane Response, Development, and External Relations Directorate, states that the findings compile nearly two decades of evidence on the impact of vaccination. “There’s been individual studies that have looked at this question of HPV vaccine and cervical cancer,” he explains, “but it’s only recently that we actually have data on cervical cancer itself.” Girls who received the first HPV vaccines in 2006 are only now reaching their 30s—an age when cervical cancer begins to appear—finally allowing researchers to measure long-term outcomes.
Strong protection in randomized trials
The first Cochrane review focused on randomized controlled trials, the gold standard for evaluating medical interventions. Drawing on 60 trials involving more than 157,000 participants, the authors found “really strong evidence,” Henschke says, that HPV vaccines prevent the infections that ultimately lead to cancer, as well as the pre-cancerous cervical lesions that are an earlier warning sign.
Trials consistently showed reductions in high-risk HPV infections and in CIN2+ and CIN3+ lesions in vaccinated people aged 15 to 25. They also confirmed that vaccines such as Cervarix, Gardasil, and Gardasil-9 significantly reduce anogenital warts for those exposed to the HPV types covered by each vaccine.
However, the trials had important limitations. Early studies did not include participants younger than 15 because cervical sampling in girls under 15 was considered unethical at the time. “That was problematic,” Henschke notes, because some participants in the trials had already been exposed to HPV through sexual activity, making it harder to measure vaccine benefits. And because cancer takes many years to develop, the trials could not capture long-term cancer outcomes.
Still, across these controlled clinical environments, the vaccines showed no increase in serious adverse events. Mild, short-lived symptoms such as injection-site pain were common, but serious outcomes were rare and occurred at similar rates in vaccinated and control groups.
Large population studies confirm cancer prevention
The second Cochrane review addressed the limitations of clinical trials by analyzing real-world, population-level evidence: 225 observational studies involving more than 132 million people. These studies followed vaccinated and unvaccinated groups over time—some for as long as 20 to 40 years—to examine HPV infections, pre-cancerous lesions, and cervical cancer itself.
Here, the evidence was striking. Girls vaccinated before age 16 were 80% less likely to develop cervical cancer than their unvaccinated counterparts. Across all ages and study designs, the reduction in cervical cancer was 63%.
“That’s kind of our key result,” Henschke says, “and it really shows across the different outcomes that early vaccination is really important.”
The review also confirmed major reductions in pre-cancerous cervical changes and in anogenital warts. For males—who began receiving the vaccine later—emerging long-term data suggest protection against penile and anal cancers.
Addressing safety concerns
A major component of the second review involved assessing claims of safety risks widely discussed online. The research team systematically searched platforms like Twitter and WebMD to identify the conditions people most often linked to HPV vaccination—postural orthostatic tachycardia syndrome (POTS), chronic fatigue syndrome, complex regional pain syndrome, premature ovarian failure, infertility, and even concerns about increased sexual activity.
“We tried to look for evidence around these specifically,” Henschke says. “Across the board, we were pretty confident that there’s no increased association of these diseases with the HPV vaccines.”
By comparing these alleged adverse events with real-world registry data, the authors found no indication that HPV vaccination increases the risk of serious or chronic conditions.
For clinicians, Henschke says the takeaway is clear: “We are a lot more confident with the information we share with patients. Now we have long-term, higher-certainty results that this is going to be effective—not just for preventing cervical cancer, but also for other outcomes.”
A global public health success story
The two new Cochrane reviews are some of the most comprehensive and up-to-date syntheses of HPV vaccine evidence. They reaffirm global recommendations to vaccinate both girls and boys before age 16, ideally before any exposure to HPV.
Looking ahead, researchers expect more data over the next decade on male cancers and on long-term outcomes as vaccinated populations age. But the message from today’s evidence is already unequivocal.
“We now have clear and consistent evidence from around the world that HPV vaccination prevents cervical cancer,” Henschke says. “And the commonly reported side effects—often discussed on social media—were found to hold no evidence of a real link to vaccination.”
With more than 300,000 cervical cancer deaths each year worldwide, mostly in low- and middle-income countries, the global impact of HPV vaccination could be transformative. As these reviews show, it is also one of the safest and most effective cancer-prevention tools available today.
