The HPV vaccine: how it works and who it's for

Human papillomavirus (HPV) is the most common sexually transmitted infection (STI) (CDC, 2019-a). In fact, more than 80% of sexually active people will get HPV in their lifetime. (NFID, 2019) Approximately 79 million Americans currently have HPV with about 14 million new cases each year. (CDC, 2019-a).

There are many different types of HPV; over 200 have been identified, and at least 40 are known to affect the genital area. The virus is usually harmless and goes away on its own; however, some strains have been linked to cancers, genital warts, and skin warts, among other conditions. The HPV vaccine was developed to prevent infection with these more worrisome strains; these include HPV types 6, 11, 16, 18, 31, 33, 45, 52, and 58.

What is so special about these types? These nine strains are the ones most commonly linked with HPV-related cancers and genital warts. HPV types 6 and 11 cause over 90% of genital warts; they are not associated with cancer. Types 16 and 18 are referred to as “high-risk HPV” because they are strongly associated with a variety of cancers; these two HPV types cause 64% of invasive HPV-related cancers. HPV-associated cancers include cervical, vulvar, and vaginal cancer in women, penile cancer in men, and oropharyngeal and anal cancers in both women and men. (CDC, 2015) An additional 10% of these cancers are linked to HPV types 31, 33, 45, 52, and 58 (CDC, 2015).

The strains you are protected against will vary depending on which HPV vaccine you receive. Currently, the U.S. Food and Drug Administration (FDA) has approved three HPV vaccines:

• Gardasil by Merck was approved in 2006 and covers HPV types 6, 11, 16, and 18

• Cervarix by GlaxoSmithKline was approved in 2009 and covers HPV types 16 and 18

• Gardasil 9 by Merck was approved in 2014 and covers HPV types 6, 11, 16, 18, 31, 33, 45, 52, and 58

HPV vaccines use proteins, and not viral RNA or DNA, from the specific HPV types to create immunity in your body. They cannot cause an HPV infection. It is typically given in the muscle of the upper arm or the muscles of the upper thigh.

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The availability of the HPV vaccine has become widespread since its approval. However, when it was initially released, there was some controversy and reluctance on the part of parents to have their children vaccinated. One issue was the lack of knowledge regarding the need for the vaccine and the diseases attributed to the high-risk HPV strains. (Holman, 2014) Since HPV can be transmitted sexually, some people felt that giving it to pre-adolescent children was unnecessary as their child was not sexually active. (Holman, 2014) However, the vaccine is most effective when given before a person’s first sexual contact. Using the vaccine in boys was also a point of contention initially; HPV was not thought to cause as much long-term harm in men as in women. Now we know that the high-risk HPV strains are implicated in cancers and other health problems in both men and women.

The HPV vaccine is not only effective against preventing infection with certain strains of HPV, but it is also a very safe vaccine. Nothing in medicine is without risk, so it is important to understand both the risks and benefits of any intervention. Most people who get the vaccine do not have any side effects and, of those who do, most are mild; 92% of side effects were classified as non-serious (CDC, 2019). The Centers for Disease Control and Prevention (CDC) report that the most common side effects of the vaccine are: (CDC, 2019)

• Syncope (fainting) 

• Dizziness

• Nausea

• Headache

• Fever

• Injection site reactions (pain, swelling, and redness)

Some people are allergic to specific components of vaccines. You should let your healthcare provider know about all your allergies before any vaccine administration.

Most of the 79 million people in the United States who are infected with HPV are men and women in their late teens and early 20s. (CDC, 2019) HPV can cause serious illnesses in both men and women many years after the primary infection. For the vaccine to be most effective, it needs to be administered before the start of sexual activity. The CDC recommends giving the HPV vaccine to both boys and girls. It is routinely given at 11 or 12 years of age, but it may be administered as early as age 9 through age 26 (MMWR, 2015). If you are aged 27-45 years and are not adequately vaccinated, you should talk to your healthcare provider; together, you will decide whether the vaccine is right for you. HPV vaccines are not licensed for use in adults aged >45 years (MMWR, 2019).

People who should not get the HPV vaccine: (VIS, 2019)

• People who have had a severe and life-threatening allergic reaction to a dose of the HPV vaccine should not get another dose.

• Anyone who has a severe and life-threatening allergy to any component of the HPV vaccine should not get the vaccine. You should not get the vaccine if you are hypersensitive to yeast as it is one of the main components of the vaccine. 

• Pregnant women should not get the HPV vaccine. However, women who are breastfeeding can get vaccinated.

Depending on your age when you first get the vaccine, you may be on a 2-dose or a 3-dose schedule (CDC, 2019-b). The 2-dose schedule is recommended for people who receive the first dose between the ages of 9-14. A second dose should be given 6–12 months after the first dose. If the second dose is given less than five months after the first dose, you need to get a third dose. The 3-dose vaccine series is for people who get the first dose of the vaccine at age 15 or older and for people with weakened immune systems. The second dose is then given 1-2 months after the first, and the third dose is given six months after the first dose.

So far, clinical trials have followed vaccinated people for ten years. There does not appear to be any decrease in the protection against HPV infection over time.

Talk to your healthcare provider about whether the HPV vaccine is right for you. You can get the vaccine from your primary care doctor, gynecologist, pharmacist, or other healthcare providers. Most health insurance plans cover the HPV vaccine for the approved vaccination schedule.

Routine HPV vaccination has been around since 2006 for girls/young women and since 2011 for boys/young men. The increase in vaccinations has caused a significant decrease in the number of HPV infections (for the types targeted by the vaccine), along with a reduction in the rate of genital warts and cervical precancers when compared with the rates in the pre-vaccine era. (MMWR- 2019) According to the CDC, infections with the HPV types that cause most HPV cancers and genital warts have dropped 86 percent in teenage girls. In young adult women, they have dropped 71 percent. Lastly, the percentage of precancerous cervical lesions (lesions that can develop into cervical cancer if left untreated) has fallen by 40 percent in vaccinated women. (CDC, 2019).

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Current version

September 06, 2019

Written by

Chimene Richa, MD

Fact checked by

Tzvi Doron, DO

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About the medical reviewer

Tzvi Doron, DO

Dr. Tzvi Doron is Board Certified in Family Medicine by the American Board of Family Medicine.