People vaccinated against the human papillomavirus (HPV) were much less likely to develop cancers of the head and neck, according to a study published this week in the International Journal of Infectious Diseases.
The study confirms earlier research finding a vaccine-related decrease in head and neck cancers.
The new study analyzed 1.4 million medical records from 66 US healthcare organizations. Half of the research subjects were vaccinated against HPV from ages 9 to 45. The other half were vaccinated against other diseases but not HPV. Study participants were vaccinated from January 2011 to June 2024.
People vaccinated from age 9 to 26 years—the age range recommended by the American Academy of Pediatrics—were 68% less likely to be diagnosed as having head or neck cancer, according to the study.
There was no statistically significant reduction in head and neck cancers in people vaccinated from age 27 to 45, most likely because these people had been exposed to HPV before being immunized, said Ching-Nung Wu, MD, PhD, first author of the paper and an otolaryngologist at Kaohsiung Chang Gung Memorial Hospital in Taiwan.
A common cause of cancer
HPV causes nearly all cases of cervical cancer, along with more than 90% of anal cancers, 75% of vaginal cancers, 70% of vulvar and head and neck cancers, and 63% of penile cancers.
A study published in December 2025 found the vaccine reduces the risk of tumors of the vagina and vulva. A study published in April found that 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.
Although head and neck cancers were once caused mostly by tobacco and alcohol use, most of these tumors are now caused by HPV. Cancers related to HPV tend to develop in an area called the oropharynx, which includes the tonsils, base of the tongue, back part of the roof of the mouth, and the side and back walls of the throat.
In the new study, people vaccinated against HPV were 91% less likely to be diagnosed as having oropharyngeal cancers.
Statistical uncertainty
Independent scientists note that the total number of head and neck cancers diagnosed among study participants was very small, with 40 among people vaccinated against HPV and 130 in the comparison group. Oropharyngeal cancers made up a fraction of these tumors.
That makes it tricky to estimate the exact reduction in risk, said Taito Kitano, DrPH, a researcher at Nara Prefecture General Medical Center in Nara, Japan, who was not involved in the new study.
Although Wu and his colleagues followed up with study participants for 13 years after the patients were vaccinated, that may not have been a long enough time to judge their cancer risk. Head and neck cancers are typically diagnosed in older men, at an average age of 64, according to the American Cancer Society.
“These figures should be read as an observational association, not a precise causal estimate of vaccine effectiveness,” Wu told CIDRAP News.
These figures should be read as an observational association, not a precise causal estimate of vaccine effectiveness.
“What gives us confidence in the overall direction, rather than the exact magnitude, is the consistency of the findings: The protective association held across cancer subsites, across subgroups, and persisted five to 13 years after vaccination, and it is biologically plausible given HPV's established causal role in oropharyngeal cancer.”
Larger study needed
To truly understand how many oropharyngeal cancers are prevented with HPV vaccines, Kitano said scientists would have to perform a larger study and follow participants for a longer time.
In spite of the study’s limitations, “it is a good trend and something we should continue to follow over time,” said Mark Einstein, MD, chair of obstetrics and gynecology and women’s health at Montefiore Medical Center in New York.
