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In 2006, a vaccine became available to protect against infections associated with two strains of the human papillomavirus (HPV). It was a potential game-changer: These strains cause 70% of cervical cancers, 90% of anal cancers, and about 75% of the cancers that affect the throat.

Newer generations of this vaccine are generally recommended for people ages 9 to 26. Although there is a focus on pediatricians vaccinating preteens and young teens prior to their becoming sexually active, catch-up vaccination is generally recommended through age 26, and the vaccine has in fact been approved in the U.S. through age 45.

Despite HPV’s prevalence—13 million Americans become infected with HPV each year—and the vaccine’s protective benefits, just 60% of American adolescents are up to date with their HPV vaccinations. By 2030, the U.S. Department of Health and Human Services aims to reach 80%, on par with Australia, the United Kingdom, and many European countries.

Oral pathologist Mark Lerman, A97, D02, chair of the Department of Diagnostic Science at Tufts University School of Dental Medicine, explains the origins of vaccine reluctance; the benefits of vaccination; and how people who came of age before it arrived can still protect themselves from HPV-related cancers.

What’s the importance of the HPV vaccine from an oral health standpoint? We often hear about it from a sexual health perspective, but it has other implications, too.

The importance of the HPV vaccine from a standpoint of oral health is that it protects against cancers that result from HPV infection, including oropharyngeal cancers. Approximately 80% of oropharyngeal cancers are associated with HPV and could potentially be prevented with the vaccine. It should be emphasized that it is intended as a preventive measure and it is not intended as a treatment.

It’s important to clarify the distinction between oral cancers and oropharyngeal cancers. The oral cavity refers to the front part of the tongue and the floor of the mouth, where we’ve traditionally seen a number of cancers, many of which are smoking- or alcohol-related. For oral cancers, it’s not that there’s no relationship with HPV, but it’s significantly less than in the oropharynx: About 5% of oral cavity cancers are HPV-related.

The oropharynx refers more generally to the back of the throat, the tonsils, and the base of the tongue.

There are several strains of HPV, and they’re not all created equal. Which ones are worse?

Correct: There are more than 200 types of HPV, many of which are low-risk. They cause benign warts on the skin or other innocuous oral findings, such as squamous papillomas, which are among the most common findings seen in the oral cavity.

But then there are high-risk types of HPV, by which we mean types of HPV that don’t necessarily always cause cancer, but they may be the ones in which persistent infection can lead to cancer. I phrase it that way because many people could be exposed to any type of HPV, low-risk or high-risk, and clear the virus in a short time, for reasons that we don’t fully understand yet.

On the other hand, some people are chronic carriers of HPV, and it’s these chronic carriers of the high-risk types of HPV that seemingly are the ones who go on to develop cancer. There are multiple high-risk types of HPV; Type 16 and Type 18 are probably the two best recognized, most common, and most likely to cause oropharyngeal cancers.

How many vaccines are needed? Do you need boosters?

For individuals receiving their first dose between the ages of 9 and 14, a second dose should be given six to 12 months after the first. For individuals receiving their first dose at age 15 or older, a second dose should be given one to two months after the first, with a third dose added six months after the first. Additional boosters are not recommended currently, though the duration of protection is still unclear. Changes to the dosing regimen could potentially be considered as vaccine study participants are followed over time.

Let’s talk about the importance of the HPV vaccine for teens and young people. In the United States, the vaccine rate for those eligible is around 60%, and the goal is 80%. Our rate is also lower than our peer countries. Why?

The vaccination uptake rates here in the U.S. are about 60%. Australia, the U.K., and much of Europe are around that 80% mark, where we’d ideally like to be.

There are different reasons for vaccine hesitancy. Recent studies evaluated some of the reasons that parents cite for declining to vaccinate their children, ranging from concerns that the vaccines are unnecessary to unsafe.

Previously, many parents felt that their children’s not being sexually active yet was a reason not to vaccinate them. And parents might worry that a vaccine may promote early sexual behaviors, but the idea is to begin vaccinating children before they become sexually active. It’s intended as a preventive measure. This reasoning has become less of a factor in recent years.

A more common reason today is that there’s a lot of misinformation about the vaccine, often spread by social media. There have been myths about autism, multiple sclerosis, autoimmune diseases, and ovarian failure. The reality is that a lot of the concerns about the safety of the vaccine have been scientifically debunked.

What are possible side effects?

Clinical trials have demonstrated the safety of the HPV vaccines. The most common adverse effects are mild-moderate injection site reactions, with some patients reporting systemic adverse effects including headache, fever, nausea, or dizziness. Large studies have not supported anecdotal reports raising concern for multiple sclerosis and other demyelinating disorders.

What’s the prognosis for HPV-related cancers?

Again, I’ll distinguish between oral cancers and oropharyngeal cancers. What we have seen is that oropharyngeal cancers that are HPV-driven do have a better prognosis than the minority of oropharyngeal cancers that have no relationship with HPV. The former tend to be more responsive to treatment. While oropharyngeal cancers across the board have a 5-year-survival rate of approximately 50%, oropharyngeal cancers that are associated with HPV have a 5-year-survival of approximately 80%.

That is why any time someone is diagnosed with oropharyngeal cancer today, it is standard practice for the patient to be evaluated to see if it’s related to HPV.

But of note: For those patients who have oropharyngeal cancers that are HPV-positive, but who also have the risk factors of cigarette smoking or heavy alcohol consumption, this seems to negate a positive relationship outcome. For reasons we may not fully understand, the risk factors of smoking and drinking seem to outweigh the HPV factor in terms of determining prognosis.

Interestingly, in the limited number of oral cavity cancers that are HPV-related—again, there may be 5% or so—we really haven’t seen any difference in behavior between the HPV-positive and the HPV-negative oral cavity cancers to date.

How long does it take for HPV to cause problems, and what are the symptoms?

Oropharyngeal cancer is generally not diagnosed before middle-age. Therefore, because most of the people vaccinated would not have developed cancers until decades later, we may have yet to see the impact of vaccination in large scale studies.

Symptoms of oropharyngeal cancers can be subtle and somewhat generic, like a sore throat. Maybe they’ll have swelling of the lymph nodes, hoarseness, pain upon swallowing, or earaches. But these are symptoms that can be mistaken for much more common findings, like the common cold.

We don’t necessarily recommend invasive testing for anyone who has those symptoms for a short time, but if they persist for longer than would otherwise be expected for a common cold or another infection, that’s when it might be worth further evaluation.

What about prevention, specifically for people who have already aged out of the recommended vaccination group?

Smoking and alcohol are risk factors that may be somewhat easier to identify. But for HPV-related cancers, the modes of transmission are believed to include both sexual and non-sexual contact, which complicates efforts to reduce the risk of HPV exposure.

Otherwise, have regular dental checkups and try to be as attuned as possible to any of these admittedly nonspecific symptoms that might persist. Again, those features are seen in common colds. If they’ve gone on for more than a couple of weeks, then it may be time to have a professional evaluation.