Human papillomavirus, or HPV, is a group of more than 200 related viruses that are spread by skin-to-skin and sexual contact. Not only is it the most common sexually transmitted infection in the United States, but about half of the infections are with high-risk strains that are responsible for roughly 3% of all cancers in people assigned female at birth and 2% in those assigned male.
Fortunately, there’s a vaccine for HPV — and thanks to an October 2018 decision by the Food and Drug Administration, Gardasil 9 (the latest version of the vaccine) was approved for people up to age 45. That means people who were past the previous age limit of 26 have the green light to get catch-up jabs.
HPV vaccination isn’t recommended for all adults ages 27 to 45, though. The Centers for Disease Control and Prevention states the option doesn’t need to be discussed with most adults in this age group — which could explain why a 2020 national survey found that over 60% of adults in this age bracket are unaware it’s approved for them.
So now that you’re in the know, how old is too old for the HPV vaccine? It depends, according to experts.
First, A Crash Course On The HPV Vaccine
There are 15 types of HPV that are characterized as high-risk. Two types ― 16 and 18 ― are responsible for most cervical cancers and pre-cancers, as well as many cancers of the vulva, vagina, penis, anus and throat, according to the American Cancer Society.
Gardasil 9 protects against nine types of HPV, including seven high-risk HPV types that cause most HPV-related cancers (16 and 18 among them), plus two low-risk HPV types that cause most genital warts.
“HPV vaccines stimulate the body to produce antibodies,” explained Heather Brandt, a behavioral scientist at St. Jude Children’s Research Hospital in Memphis, Tennessee. “These antibodies, in future encounters with HPV, protect someone from becoming infected.”
Gardasil 9 is made up of virus-like particles, which are essentially knockoffs of the HPV virus. They aren’t infectious in that they lack the virus’ DNA, Brandt explained, but they look enough like it to the immune system that the antibodies produced against the virus-like particles also work against the actual virus.
Virus-like particles “have been found to induce high levels of antibody production by the body, which is why the HPV vaccine works so well,” Brandt said.
Why The HPV Vaccine Is Less Effective When You’re Older
The immune response to the vaccine gets weaker as you age (it starts to dwindle as early as your late teens, according to the American Cancer Society) and it can’t protect you against any HPV strains you’ve already been exposed to. So it was originally thought the vaccine wouldn’t provide much benefit for cancer prevention past 26 years of age.
What changed? Since vaccinating against HPV is most effective prior to any exposure, “the original studies were done in girls and younger women, who likely hadn’t been exposed to HPV,” said Dr. Jill Purdie, board-certified OB/GYN and medical director at Pediatrix Medical Group in Atlanta.
It wasn’t until later that studies were done in women up to age 45. The one that moved the needle for the FDA found that Gardasil 9 was still 88% effective in the prevention of vulvar, vaginal and cervical precancerous lesions, cervical cancer and genital warts caused by the nine HPV strains, even in people assigned female at birth who may have been exposed to the virus already. (The effectiveness of the vaccine in people assigned male at birth was inferred from this data, too.)
“This is because it’s unlikely they were exposed to all the HPV types, so the vaccine still offers some protection,” Purdie said.
Still, it’s important to keep in mind your response to the vaccine might not be as robust; the vaccine’s effectiveness is highly individualized and influenced by your history of prior HPV infections.
How To Decide Whether Getting The HPV Vaccine Is Right For You
Until now, the assumption that you’ve already been exposed to various HPV strains may have left you wondering whether getting catch-up vaccines is worth the effort.
The best way to decide is to go through a process called “shared clinical decision-making,” where you and your doctor determine together how much you’ll realistically benefit from this particular series of shots, according to the Advisory Committee on Immunization Practices.
“There’s limited guidance on how exactly to apply the recommended [shared clinical decision-making] approach,” Brandt said, in large part so the decision-making remains flexible and highly individualized to your situation.
But there are several factors to be considered by you and your doctor, including:
- Previous evidence of HPV
- Risk of HPV cancer, based on medical history and possible level of exposure
- Relationship status
- Cost and access to coverage of vaccination costs
- Understanding the likelihood of reduced protection
You unequivocally shouldn’t get the HPV vaccine if you’ve ever had a severe allergic reaction to any ingredient of an HPV vaccine or a previous dose of the HPV vaccine itself, have an allergy to yeast (Gardasil 9 contains yeast protein), or are pregnant, according to the CDC.
Ultimately, what matters most is your peace of mind: “I do feel that getting vaccinated, even if you’ve already been exposed to HPV, is helpful since it’s unlikely a person has been exposed to all the types the vaccine protects against,” Purdie said.
What if you’re over 45 and want to get vaccinated? “Administration after 45 is considered off-label,” Brandt said, so insurance may not cover your vaccinations. (“On average, each dose costs around $250 if not covered, with three doses being the requirement,” Purdie said.)
Unless you have an allergy to ingredients in the vaccine or are pregnant, there’s no harm or risk in getting vaccinated, Brandt said. The chance of protection against even a fraction of the high-risk HPV strains is worth a shot (pun totally intended).