Human papillomavirus (HPV) is one of the most common sexually transmitted infections, with an estimated 79 million Americans currently infected and about 14 million new infections every year. HPV is usually harmless and goes away on its own, but some types can lead to cancer or genital warts.
The HPV vaccine protects against the types of HPV that most commonly cause cancer and warts. The vaccine is recommended for preteens aged 11-12 years old, but can be given as early as age 9. The vaccine is also recommended for teens and young adults who have not yet received it.
How Long Does HPV Vaccine Protection Last?
Studies have shown that the HPV vaccine provides long-lasting protection against the HPV types covered by the vaccine. However, exactly how long the protection lasts is still being determined through ongoing research.
Here’s what we know so far about how long the HPV vaccine protects against HPV:
- Clinical trials have followed vaccinated individuals for over 10 years and have shown the antibodies produced by the vaccine persist in the body and provide protection for at least that long.
- Modeling studies estimate the vaccine protection will continue past 10 years and could be lifelong in many individuals.
- Most vaccinated individuals who participate in ongoing research continue to have HPV antibody levels that are as high or higher than levels in people who have naturally cleared an HPV infection.
- So far, studies have not detected evidence of decreased protection over time.
Based on the evidence, researchers state that HPV vaccine protection is expected to be long-lasting. More time is needed to determine if protection extends for the lifetime of individuals who are vaccinated.
Why Won’t We Know if Protection is Lifelong Sooner?
There are a few reasons why it will take more time to determine if HPV vaccine protection truly lasts a lifetime:
- Time: The HPV vaccines have not been in use long enough to directly evaluate lifelong protection. The first HPV vaccine was approved in 2006. Researchers need more time to follow vaccinated individuals for decades to directly demonstrate lifelong immunity.
- Study design: The initial clinical trials tested efficacy for 4-6 years after vaccination to allow licensing of the vaccines. Long-term studies now following vaccine recipients for decades are observational (looking back at existing data) rather than controlled trials.
- Rare outcomes: Cervical and other cancers caused by HPV take years or decades to develop. Large sample sizes and long follow-up periods are needed to obtain enough outcomes to directly measure if risk reduction remains decades after vaccination.
- HPV exposure: It’s unethical to intentionally expose vaccinated people to HPV. Whether their antibody levels would protect against new infection can only be inferred through measurements.
- Changes over time: HPV types can evolve over time. Ongoing research must monitor for potential immune escape or vaccine evasion by new HPV variants.
Despite these limitations, researchers remain confident that HPV vaccine protection will be extremely long-lasting, possibly for life, based on all available data on antibody persistence and continued production in response to natural HPV exposure.
Evidence of Long-Lasting Protection
Here is more detail on some of the key evidence supporting long-term efficacy of the HPV vaccine:
Clinical Trial Follow-Up
In the initial clinical trials for both Gardasil and Cervarix, participants were followed for an average of 3-5 years. These studies found the vaccines were fully protective against persistent HPV 16/18 infections and disease during that time period.
For Gardasil, follow-up was extended to 10 years after vaccination through an extension study. This study found no cases of HPV 16/18 related diseases in the vaccinated group, while there were cases in the unvaccinated group. Antibody levels remained high 10 years after vaccination.
Population-Based Studies
In countries like Australia and Scotland where HPV vaccination programs have been in place for over a decade, researchers have been able to evaluate long-term real world efficacy. The results consistently show the vaccines continue to provide protection against HPV infections and precancerous lesions beyond 10 years.
For example, a 2021 study in Scotland found that in routinely vaccinated young women, cases of high-grade cervical abnormalities were 89% lower compared to unvaccinated women. This high level of protection was maintained over 8 years of follow-up.
Immunogenicity Studies
Multiple studies have measured antibody levels against HPV in vaccinated individuals years later. These immunogenicity studies show antibody levels remain high or even increase for at least 10-15 years after vaccination.
In a U.S. study published in 2020, 99% of vaccinated women continued to have detectable HPV 16 and 18 antibodies 9-12 years after vaccination. Antibody levels were actually higher at follow-up than after the 3-year booster dose.
Mathematical Models
Researchers have used mathematical models to estimate how long HPV vaccine protection could last based on what we know about antibody decay rates. These models consistently estimate decades of protection, with some showing protection could last 60-100 years in many vaccinated people.
More data will be needed to refine the models over time. But so far, the predictions align with the clinical evidence that efficacy will be extremely durable.
Possibility of Additional Doses
Based on current evidence, HPV vaccination provides long-term protection and additional booster doses beyond the initial series are not recommended. However, recommendations could possibly change in the future if more data suggests immunity may begin to wane after some point.
In one recent 2021 study, researchers did find slight declines in antibody levels around 20 years after vaccination. Some experts think booster doses may eventually be warranted after mid-adulthood.
More data is still needed, and models suggest antibody levels would remain in the protective range decades after vaccination. But if further evidence shows a concerning drop off in efficacy over time, boosters could be recommended to maintain protection.
Impact of HPV Infection After Vaccination
Another area of ongoing research is understanding whether getting an HPV infection could override the immune protection from vaccination. The vaccine produces very high antibody levels compared to natural infection. But it’s possible a new infection could affect long-term immunity.
So far, studies show vaccinated people who later acquire an HPV type covered by the vaccine continue to have protection against disease from that HPV type. Their antibody levels remain high.
One study found women who tested positive for a vaccine HPV type 8 years after vaccination had no increased risk for abnormalities/precancerous changes compared to HPV-negative women – their vaccine protection remained intact.
More follow-up will clarify the extent to which later HPV infections may or may not impact long-term vaccine efficacy over decades.
Table 1: Key evidence supporting long-term efficacy of HPV vaccination
| Evidence | Findings |
|---|---|
| Clinical trial extension studies | No cases of HPV disease through 10 years post-vaccination |
| Population studies | High vaccine efficacy maintained through 8+ years |
| Immunogenicity studies | Antibody levels remain high or increase over time |
| Mathematical models | Predict decades of antibody persistence |
Conclusion
In summary, while the precise duration of HPV vaccine protection is still unknown, there is strong evidence immunity will be extremely long-lasting, possibly lifetime, for most people. Ongoing research continues to find high efficacy and antibody persistence for over 10 years post-vaccination.
Mathematical models and population data also suggest protection could last many decades. Continued follow-up will determine if efficacy eventually begins to wane given enough time. But so far, all observations point towards durability of HPV vaccine protection for the long term.
Given the high efficacy over time, HPV vaccination is recommended for preteens to provide protection during the ages when HPV exposure typically occurs. Even if booster doses eventually prove necessary, the initial vaccination series in adolescence can provide protection when it is needed most through the early adult years and beyond.