The human papillomavirus (HPV) vaccine helps prevent HPV infections that can lead to certain cancers. HPV vaccines like Gardasil and Cervarix provide strong protection against cervical, vaginal, and vulvar cancers in women and against anal cancer and genital warts in both women and men. Getting vaccinated at the recommended age before being exposed to HPV is important to get the most protection.
How many doses of the HPV vaccine are recommended?
The current recommendation is 2 or 3 doses of the HPV vaccine, depending on age at initial vaccination:
- If the series is started before age 15, two doses of the HPV vaccine at least 6-12 months apart are recommended.
- If the series is started at age 15 or older, three doses of the HPV vaccine at 0, 1-2, and 6 months are recommended.
The original HPV vaccine recommendation was for three doses for everyone, but studies showed two doses were as effective for younger adolescents. The two-dose schedule applies only if the first dose is given before age 15. Teens and young adults who start the series at age 15 or older still need the full three-dose series.
Why are fewer HPV vaccine doses recommended for younger adolescents?
Research has shown that younger adolescents respond better to the HPV vaccine and have higher HPV antibody levels after vaccination compared to older teens and young adults. The strong immune response in preteens allows the two-dose schedule to provide similar protection as three doses in this age group.
The CDC changed the recommendation to a two-dose schedule for 9-14 year olds in 2016 based on data from clinical trials and post-licensure monitoring. Studies found the antibody responses in younger adolescents were as good or better with two doses compared to three doses in older groups. This data showed two doses given at least five months apart provide similar efficacy against HPV infection and disease as three doses in the younger age bracket.
What are the two-dose and three-dose schedules for HPV vaccination?
For children starting the HPV vaccine before their 15th birthday, two doses are recommended:
- First dose: At 11-12 years old
- Second dose: 6-12 months after the first dose
For adolescents starting the vaccine at 15 or older, and adults, three doses are recommended:
- First dose: Day 1
- Second dose: 1-2 months after first dose
- Third dose: 6 months after first dose
Ideally, the vaccine series should be completed before potential exposure to HPV through sexual contact. However, vaccination may be given after exposure or even after initial infection to protect against additional HPV types. Talk to your doctor about catch-up vaccination if doses were missed or given too close together.
What if the HPV vaccine schedule is interrupted?
If the HPV vaccine schedule is interrupted, the series does not need to be restarted. Rather, vaccination should be resumed as soon as possible with the next recommended dose, without repeating prior doses. The minimum intervals between doses should be maintained whenever possible.
Examples of how to catch-up when doses are delayed:
- If the second dose was delayed, it should be given as soon as possible with at least a 12 week interval from the first dose.
- If the third dose was delayed, it should be given as soon as possible with at least a 12 week interval from the second dose and 24 week interval from the first dose.
Can the HPV vaccine be given at the same time as other vaccines?
Yes, the HPV vaccine can be administered at the same time as other vaccines recommended for the same age, such as the meningococcal and Tdap vaccines.
When given together, each vaccine should be injected at a different site on the body without compromising dosage or safety. The vaccines help protect against different infections and none of them interfere with the immune response to the others.
How effective is two doses versus three doses of the HPV vaccine?
Multiple large studies found two doses of the HPV vaccine were just as effective as three doses when given to younger adolescents before age 15.
One study followed girls aged 9-13 who received two or three doses of the HPV vaccine. After up to nine years of follow-up, there was no difference in risk of HPV infection between the two- and three-dose groups. Both had zero cases of HPV types 16 and 18, demonstrating nearly 100% vaccine efficacy.
Another study found girls aged 9-14 who received two doses of the HPV vaccine six months apart had antibody levels 1.4 to 2 times higher than women 16-26 years old given three doses. The results support the finding that two doses provide strong protection in the younger age group.
The efficacy of two doses was also similar to three doses in real-world evidence from public health vaccination programs. A 2020 study from Mexico found the prevalence of targeted HPV types decreased by 93% in 15-19 year old girls five years after introduction of a two-dose HPV vaccination program.
Efficacy of two-dose vs three-dose HPV vaccination:
| Study Group | Schedule | Effectiveness |
| Girls age 9-13 | 2 doses | 100% for HPV 16/18 |
| Girls age 9-13 | 3 doses | 100% for HPV 16/18 |
| Girls age 9-14 | 2 doses | Higher antibody response than 3 doses in older girls |
| Girls age 15-19 | 2 doses | 93% decrease in HPV prevalence |
In summary, multiple studies confirm two doses of the HPV vaccine are equivalent to three doses when given to young adolescents under 15. Both schedules provide over 90% protection against the HPV types that cause the majority of cancers.
Are three doses better for longer protection or those at higher risk?
Currently, there is no evidence that three doses of the HPV vaccine give longer-lasting immunity compared to two doses in younger adolescents. Protection has been shown to last at least 10 years with two doses started before age 15.
Likewise, three doses are not considered necessary for groups at higher risk of sexual exposure or HPV infection, as long as the two-dose series is started before age 15. The priority is giving the vaccine at the target age to maximize immune response before exposure.
However, if the series is started at age 15 or older, three doses are still recommended for longer-lasting protection. Older teens and young adults are likely to have been exposed to HPV already and may not respond as robustly to the vaccine. But receiving three doses between ages 15-26 can still reduce the risk of future HPV infection and disease.
Are HPV vaccine recommendations likely to change in the future?
Current HPV vaccine recommendations may continue to evolve as more long-term effectiveness data become available. Some changes under consideration include:
- Lowering the age cutoff for the two-dose schedule to under 15
- Lengthening minimum dose intervals to allow more flexibility
- Simplifying to a two-dose schedule for everyone under 15-18 years old
The guidelines may also expand to include more groups not currently included in HPV vaccination recommendations, such as:
- Boys and adult males under age 26
- Adults over age 26 who are at higher risk or want protection
- Immunocompromised persons requiring more doses
To ensure you receive the ideal HPV vaccine schedule, check the latest recommendations when scheduling vaccination for yourself or your child. Stay up to date on any changes that provide extended protection.
Conclusion
In summary, current HPV immunization guidelines recommend two doses for children under 15 years old and three doses for older adolescents and young adults. The two-dose schedule spaced at least six months apart provides equivalent protection for younger teens compared to the three-dose series.
Starting vaccination at 11-12 years old maximizes immune response and allows for fewer doses. However, older teens and young adults up to age 26 can still benefit from HPV vaccination. Follow your doctor or health department’s advice on receiving the HPV vaccine series.
Ask your provider any other questions you have about HPV vaccination, such as vaccine types, side effects, or insurance coverage. Be sure your child receives all recommended doses of the HPV vaccine for lifelong protection against cancers caused by HPV infection.