The Benefits and Side Effects of the HPV Vaccine

There are risks associated with the human papillomavirus (HPV) vaccine, but evidence has shown that the benefits—namely preventing certain types of cancer—greatly outweigh the risks.

Most new HPV infections occur in teens and young adults who have no idea they have been infected, allowing them to pass the virus to their sexual partners without realizing it. With no cure yet in sight, the best defense against HPV is vaccination.

To this end, the Centers for Disease Control and Prevention (CDC) recommends that all children be vaccinated against HPV at ages 11 to 12, and even allows for vaccination up to age 45 for some people.

World immunization week and International HPV awareness day concept. Woman having vaccination for influenza or flu shot or HPV prevention with syringe by nurse or medical officer.
Pornpak Khunatorn / Getty Images

What Is HPV?

Human papillomavirus (HPV) is the most common sexually transmitted infection in the United States. So common, in fact, that nearly all sexually active adults will get it at least once in their lifetime if they aren’t vaccinated against the virus.

Roughly 14 million Americans are infected every year, and, while the majority of infections will clear up on their own without symptoms or consequence, some will lead to genital warts or cancer (most often cervical cancer in women and anal cancer in men who have sex with men).

About Gardasil-9

There used to be three HPV vaccines approved for use in the United States that prevented anywhere from two to nine high-risk strains of HPV. These are the strains that are closely linked to the development of cancer.

Today, two of the vaccines—Cervarix and the original Gardasil—have been voluntarily withdrawn from the U.S. market in favor of Gardasil-9, which protects against HPV types 6, 11, 16, 18, 31, 33, 45, 52, and 58.

Gardasil-9 is administered by injection in a 0.5 milliliter (mL) dose.

Immunization Schedule 

The Advisory Committee on Immunization Practices (ACIP) recommends that children of all sexes be vaccinated against HPV starting at age 11 or 12, although the vaccine can be given to anyone from age 9 to 45.

The number and timing of doses depend on when the first dose is given: 

  • For children 9 to 14: Two doses are administered six to 12 months apart.
  • For teens and adults 15 to 45: Three doses are administered over six months.

Adults over 26 who are interested in the HPV vaccine should discuss the benefits and limitations of vaccination with their doctor. The vaccine is expected to be less effective in that group, as most people have been exposed to HPV by that age.

After age 26, the people most likely to benefit are those who have had no prior sexual activity, have had few sexual partners, or at a significantly increased risk of HPV exposure (such as having a partner with symptomatic HPV infection).

Differing from the CDC guidelines, the American Cancer Society recommends HPV vaccination starting at age 9 to increase vaccination rates. The ACS also advises against HPV vaccination after 26.

Benefits

The biggest reason to be vaccinated against HPV is that it can protect you from getting a strain that may cause cancer or genital warts. The protection appears to long-lasting, with studies suggesting a durable response of at least 10 years.

From 2012 to 2016, around 44,000 HPV-associated cancers occurred in the United States, including nearly all cervical and anal cancers and most cases of head and neck, penile, vaginal, and vulvar cancer.

While Gardasil-9 doesn’t protect against all strains of HPV, it does protect against the strains most likely to cause cancer. Among them, HPV types 16 and 18 account for around 70% of all cervical cancers.

According to the CDC, widespread HPV vaccination in children could prevent 92% of all HPV-related cancers in the United States, translating to a reduction of 32,000 cancer cases per year.

Side Effects 

As with any vaccine, Gardasil-9 may cause side effects. Most are temporary and almost always mild. The most common include:

  • Injection site redness, swelling, or soreness
  • Mild fever
  • Dizziness or lightheadedness
  • Nausea
  • Headache 
  • Fatigue 
  • Body aches

Although an allergic reaction is possible, severe reactions (including anaphylaxis) are extremely rare, occurring in roughly three of every 100,000 vaccinated people.

When to Call 911

Call 911 or seek emergency care if you experience some or all of the following signs of anaphylaxis after getting Gardasil-9:

If left untreated, anaphylaxis can lead to shock, coma, or even death.

Contraindications

While nearly everyone can safely receive the HPV vaccine, there are some who shouldn’t. According to the CDC, you should not receive Gardasil-9 if: 

  • You have had a severe allergic reaction to the HPV vaccine or any component of the vaccine in the past.
  • You are moderately or severely sick (in which case, you should wait until you recover before getting vaccinated).
  • You are pregnant. While there is no evidence that the vaccine will harm the mother or developing fetus, research is limited, and it is better to err on the side of caution just in case 

You can still get Gardasil-9 even if you’ve tested positive for HPV, as it may protect against other HPV strains. 

Ensuring Vaccine Safety

Before a vaccine is approved by the Food and Drug Administration (FDA), it is tested in at least 15,000 people during clinical trials to verify its safety and efficacy.

There are also systems in place to monitor for safety and efficacy once a vaccine like Gardasil-9 is introduced to the American marketplace. These include:

  • Vaccine Adverse Event Reporting System (VAERS): A reporting system used for research and surveillance purposes that allows anyone to report adverse events following vaccination  
  • Vaccine Safety Datalink (VSD): A group of healthcare organizations that conducts studies to see if specific side effects are linked to a particular vaccine
  • Clinical Immunization Safety Assessment (CISA) Network: A group of vaccine safety experts and organizations that study safety issues following the introduction of a vaccine 

When these systems flag a potential adverse event, the ACIP reviews the evidence and adjusts their recommendations if needed.

After Gardasil-9 was released in 2016, reports of syncope (fainting) prompted the ACIP to issue recommendations that people sit or lie down for 15 minutes after receiving the vaccine to prevent falls or injuries. 

A Word From Verywell 

If you or your child has had any adverse reaction to a vaccine in the past, let your doctor know before getting Gardasil-9. This shouldn't suggest you need to avoid the vaccine but rather that your condition be monitored after the vaccination. In the majority of cases, the benefits of HPV vaccination outweigh the risks.

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