HPV Vaccination Shows Dramatic 80% Reduction in Cervical Cancer Risk When Given Before Age 16
Key Insights
A comprehensive Cochrane (search) review analyzing data from 132 million people across 225 studies found that HPV (search) vaccination by age 16 reduces cervical cancer (search) risk by 80 percent.
A separate Costa Rican study of over 20,000 girls demonstrated that a single HPV (search) shot provides 97% protection against cancer-causing viral strains, similar to the effectiveness of two doses.
The research confirms that pre-sexual activity vaccination prevents not only HPV (search) infection and precancerous lesions but also cervical cancer (search) itself, one of the most common cancers in women.
Two major studies released this week provide compelling evidence that HPV (search) vaccination offers unprecedented protection against cervical cancer (search), with one comprehensive review showing an 80% reduction in cancer risk when vaccines are administered before age 16, while another groundbreaking trial suggests a single dose may be sufficient for protection.
Cochrane Review Demonstrates 80% Cancer Risk Reduction
An international team of researchers from Cochrane (search), a nonprofit network of health researchers and professionals, analyzed data from approximately 132 million people across 225 studies released worldwide as of September last year. The comprehensive review found that receiving the human papillomavirus (search) vaccine by age 16 reduces the risk of developing cervical cancer (search) by 80 percent.
The study suggests that vaccination at ages before experiencing sexual intercourse not only prevents HPV (search) infection and precancerous lesions, but also cervical cancer (search) itself, one of the most common cancers in women. Importantly, the research team found that the vaccination does not increase the risk of commonly cited side effects such as postural orthostatic tachycardia syndrome (search), myalgic encephalomyelitis (search), chronic fatigue syndrome (search), paralysis, premature menopause and infertility.
Single-Dose Efficacy Confirmed in Costa Rican Trial
In a separate landmark study led by the U.S. National Cancer Institute (search), researchers enrolled more than 20,000 girls between ages 12 and 16 in Costa Rica to test whether a single HPV (search) vaccination could provide adequate protection. The study tested two different HPV vaccines used around the world, giving half the girls one shot type and the rest the other. Six months later, half of the girls received a second dose of their assigned vaccine while the rest instead received an unrelated child vaccination.
After tracking participants for five years with regular cervical tests for the most cancer-prone HPV (search) strains, researchers found that a single HPV shot provided about 97% protection, similar to two doses. The findings were reported in the New England Journal of Medicine by researchers from the NCI and Costa Rica's Agency for Biomedical Research (search).
"We have the evidence and tools to eliminate cervical cancer (search). What remains is the collective will to implement them equitably, effectively, and now," wrote Dr. Ruanne Barnabas, an infectious disease specialist at Massachusetts General Hospital, in an accompanying editorial.
Global Impact and Implementation Challenges
Cervical cancer (search) kills about 340,000 women worldwide annually, and the new findings could help spur global efforts to protect more girls and young women in harder-to-reach low-income countries. In Japan, some 11,000 women are diagnosed with cervical cancer every year and around 3,000 of them die from it.
Despite the proven efficacy, vaccination coverage remains suboptimal globally. The World Health Organization estimates less than a third of adolescent girls have been vaccinated worldwide. In Japan, which stopped its strong recommendation of the vaccine in June 2013 after reports of adverse reactions but resumed recommendations in April 2022, a survey by the Japan Cancer Society (search) in October 2024 found that only about 40 percent of eligible girls had received the vaccine.
Current Vaccination Recommendations
The U.S. recommends two HPV (search) shots starting at age 11 or 12 for most girls and boys, as the virus also can cause head-and-neck and other cancers. Catch-up shots are recommended for anyone through age 26 who hasn't been vaccinated. The Centers for Disease Control and Prevention (search) has reported about 78% of 13- to 17-year-olds have gotten at least one dose.
The World Health Organization had already begun recommending either one or two doses in an effort to broaden protection, and these new findings provide additional support for simplified dosing schedules that could improve global access.
Study Limitations and Future Research
The Costa Rican study offered no information about HPV (search)-related cancers beyond the cervix, and the researchers cautioned that longer monitoring is needed. Previous studies had suggested one dose could work well, but the new findings confirm strong protection for at least five years, providing the most robust evidence to date for single-dose efficacy.