The HPV vaccine, though proven to prevent cancers, is still underutilized in the United States. Many people might be deterred by its current regimen of two or three doses.
However, recent studies suggest that a single dose of the HPV vaccine may offer sufficient protection.
HPV (human papillomavirus) is primarily transmitted through sexual activity and can lead to various types of cancer such as cervical, anal, penile, vaginal, and throat cancers. Vaccinating against HPV has the potential to prevent 90% of these cancers.
In the UK, where the vaccine program was launched in 2008, there have been no recorded instances of cervical cancer among those vaccinated at ages 12 or 13 as of 2024.
The HPV vaccination originally required a series of three doses for girls starting at age 11 and later expanded to include boys. In 2016, the Centers for Disease Control and Prevention (CDC) reduced this to two doses for individuals beginning vaccination before age 15.
In April 2024, the CDC's HPV Vaccines Work Group discussed the possibility of recommending a single-dose regimen to better align with World Health Organization (WHO) guidelines.
The WHO already recommends one or two doses for girls and young women aged 9-20 in 2022. This has prompted several countries to opt for a single-dose approach, increasing affordability and accessibility.
Currently, the CDC advises at least two doses, but a growing body of research supports the safety and efficacy of just one dose. A study published in the Journal of the National Cancer Institute in 2024 reviewed data from 13 studies supporting this claim.
"If one dose is effective, it could mean more children getting vaccinated because a single dose means less hassle and lower costs," said Linda Eckert, MD, at the University of Washington, adding that it would be especially beneficial for those without health insurance.
Initial observations on a single-dose regimen emerged from a clinical trial in Costa Rica starting in 2004. About 20% of participants received fewer than three doses but still showed low rates of cervical cancer-related infections regardless of dose number.
The first randomized controlled trial conducted in Kenya found one dose was over 97% effective against HPV16 and HPV18, which are responsible for around 70% of global cervical cancer cases.
Ruanne Barnabas, MD, leading the trials in Costa Rica and Kenya, explained that a single dose is sufficient because HPV is less able to establish infection compared to other viruses. A small antibody response can be enough to prevent infection.
The cost factor makes a single-dose regimen particularly attractive for people without insurance or those facing high healthcare expenses due to recent changes in health coverage policies and rising premiums.
Currently, the HPV vaccine is recommended for ages 11-26, but it can be given from age 9. Those aged 27-45 may also receive it after consulting with a health provider.
The cost of the vaccine is approximately $300 per dose in the US, making a single-dose regimen much more affordable for many.
While discussions on this matter were ongoing, the CDC’s Advisory Committee on Immunization Practices (ACIP) was disbanded by Secretary Robert F. Kennedy Jr. in June 2024, preventing these recommendations from reaching the full committee.
"I have no knowledge of the current status," said Oliver Brooks, MD, chair of the HPV work group before it was dissolved.
News reports indicate that Kennedy has asserted dubious claims about vaccine side effects, potentially influenced by his personal ties to lawsuits against Merck, the sole US provider of the vaccine. During his Senate confirmation hearing, he stated fees earned through referrals would go to his son.
Although getting only one dose is technically possible and some individuals are already choosing this route, it remains unofficial guidance until further notice.
Barnabas herself made sure her older child received two doses but, upon weighing evidence for the younger child, decided against the second dose, choosing to prioritize comfort. She mentioned that the vaccine sometimes causes pain or stinging sensations during administration.
The simplification of the HPV vaccination schedule could make it easier and more accessible for families facing barriers like cost, time, and access to care, thus promoting its uptake significantly.