HPV Vaccine: a case study in prevention

Few vaccines inspire as much ire, confusion and concern as HPV vaccine. But HPV vaccine is a tremendous opportunity to prevent many cancers, something that was only a dream a generation ago. Truly prevent, not just screen or detect.

Was this vaccine ever studied?

If you read one article about HPV vaccine, start with this one (Garland). This is a meta-analysis that looks at worldwide implementation and effect. The supplemental data includes huge tables of studies, what they looked at, and what kind of effectiveness rates they found. Please read it before you believe the claims that this vaccine is unstudied or unproven. 

Garland, Suzanne M., Susanne K. Kjaer, Nubia Muñoz, Stan L. Block, Darron R. Brown, Mark J. DiNubile, Brianna R. Lindsay, et al. “Impact and Effectiveness of the Quadrivalent Human Papillomavirus Vaccine: A Systematic Review of 10 Years of Real-World Experience.” Clinical Infectious Diseases 63, no. 4 (August 15, 2016): 519–27. https://doi.org/10.1093/cid/ciw354.

HPV stands for Hugely Popular Virus!

OK, it doesn’t stand for hugely popular virus, even though it is hugely popular. HPV stands for human papillomavirus. Human papillomavirus infections are extremely common. Around 85% of women and 90% of men will become infected with HPV over their lifetime. There are 14,000,000 (14 million) new infections in the US each year (Chesson). Most people are infected by age 20, or shortly after becoming sexually active.

HPV is easy to transmit. There aren’t usually any symptoms, so a person usually doesn’t know they have it and doesn’t know they are transmitting it. Likewise, there’s no way to look at someone and know if they have HPV. 

Most transmissions are sexual, but there are non-sexual modes of transmission as well (Sabeena), including mother-to-child and close contact. HPV can live on objects and be transmitted that way. And sexual transmission need not be intercourse — HPV can be transmitted through oral-oral and oral-genital contact (Dahlstrom). Roughly half of girls have HPV detected in the vagina before first vaginal intercourse (Shew). 

Mother-to-child transmission is called vertical transmission. HPV vaccination in Australia has virtually eliminated a condition in infants called recurrent respiratory papillomatosis (Novakovic), where tumors called papillomas grow along the respiratory tract. Nobody who had been vaccinated gave this infection to their baby. Every case that did happen during the study was in the baby of an unvaccinated mother.

Chesson, Harrell W., Eileen F. Dunne, Susan Hariri, and Lauri E. Markowitz. “The Estimated Lifetime Probability of Acquiring Human Papillomavirus in the United States.” Sexually Transmitted Diseases 41, no. 11 (November 2014): 660–64. https://doi.org/10.1097/OLQ.0000000000000193.

Dahlstrom, Kristina R., Ann N. Burchell, Agnihotram V. Ramanakumar, Allita Rodrigues, Pierre-Paul Tellier, James Hanley, François Coutlée, and Eduardo L. Franco. “Sexual Transmission of Oral Human Papillomavirus Infection among Men.” Cancer Epidemiology and Prevention Biomarkers, November 12, 2014. https://doi.org/10.1158/1055-9965.EPI-14-0386.

Novakovic, Daniel, Alan T. L. Cheng, Yvonne Zurynski, Robert Booy, Paul J. Walker, Robert Berkowitz, Henley Harrison, et al. “A Prospective Study of the Incidence of Juvenile-Onset Recurrent Respiratory Papillomatosis After Implementation of a National HPV Vaccination Program.” The Journal of Infectious Diseases 217, no. 2 (04 2018): 208–12. https://doi.org/10.1093/infdis/jix498.

Sabeena, Sasidharanpillai, Parvati Bhat, Veena Kamath, and Govindakarnavar Arunkumar. “Possible Non-Sexual Modes of Transmission of Human Papilloma Virus.” Journal of Obstetrics and Gynaecology Research 43, no. 3 (2017): 429–35. https://doi.org/10.1111/jog.13248.

Shew, Marcia L., Bree Weaver, Wanzhu Tu, Yan Tong, J. Dennis Fortenberry, and Darron R. Brown. “High Frequency of Human Papillomavirus Detection in the Vagina Before First Vaginal Intercourse Among Females Enrolled in a Longitudinal Cohort Study.” The Journal of Infectious Diseases 207, no. 6 (March 15, 2013): 1012–15. https://doi.org/10.1093/infdis/jis775.

Why bother with the HPV vaccine? Don’t most cases resolve on their own?

Most cases do resolve on their own, but because HPV is so common, all cases minus most cases still equals a lot of cases.

Most sources cite a rate of 14,000,000 (14 million) new infections per year in the US. Even if 90% resolve on their own, that’s still 1,400,000 (1.4 million) infections that are not resolving on their own. Per year.

But the vaccine only covers 9 strains (or 4 strains or 2 strains). If there are 100+ strains, that doesn’t seem like enough.

The 9 strains covered by the vaccine cause the gross majority of the disease.

The first HPV vaccines covered types 16 and 18. These are the highest risk for cervical cancer and cause 70% of cervical cancer cases.

The 4-strain HPV vaccine (Gardasil) covers types 6, 11, 16, and 18. Types 6 and 11 cause 90% of genital warts.

The 9-strain HPV vaccine (Gardasil 9) covers types 6, 11, 16, 18, 31, 33, 45, 52, and 58. As you saw above, 16 and 18 cause 70%, and types 31, 33, 45, 52 and 58 contribute another 20%. The 9 strains covered by this vaccine thus cover 90% of the strains of HPV causing cervical cancer.

These strains also cause significant numbers of anal, vaginal, penile, vulvar and mouth and throat cancers.

Saraiya Figure 4 caption: Population attribution of human papillomavirus (HPV) in select anogenital and head and neck cancers. A) Anogenital cancers include cervical, vaginal, vulvar, anal, and penile cancers. It should be noted that the International Agency for Research on Cancer (IARC) has defined some cancers to have strong evidence for a causal association of HPV 16 and 18 with cervical, vaginal, vulvar, anal, and penile. Percent multiple infections ranged by type of anogenital cancer: cervical 8.2%; in situ cervical 21.4%; vulvar 6.3%, in situ vulvar 7.4%, vaginal 15%, anal 11.0%, penile 11.4%. Ninety-five percent Wilson confidence limits around the prevalence estimates are presented. B) Select head and neck cancers include oropharyngeal (OP), laryngeal, and oral cavity (OC) cancers. According to IARC, there is strong evidence for a causal role of HPV 16 and 18 in oropharyngeal cancer. The oral cavity is considered to have evidence for a causal association with HPV, but some of the HPV DNA detected in tissues may not represent the true causal agent. Laryngeal cancer has limited evidence for a causal etiology with HPV; and the correlation of HPV DNA detected does not reflect the percentage that is causal. C) Percent multiple infections were similar across cancer types for OP, OC, and laryngeal cancers (4.1%). Ninety-five percent Wilson confidence limits around the prevalence estimates are presented.

Saraiya, Mona, Elizabeth R. Unger, Trevor D. Thompson, Charles F. Lynch, Brenda Y. Hernandez, Christopher W. Lyu, Martin Steinau, et al. “US Assessment of HPV Types in Cancers: Implications for Current and 9-Valent HPV Vaccines.” JNCI Journal of the National Cancer Institute 107, no. 6 (April 29, 2015). https://doi.org/10.1093/jnci/djv086.

I’ve heard this vaccine is really dangerous.

Placebo-controlled studies, including studies that used saline as the placebo, show that adverse events are primarily sore arms and syncope (fainting). Fainting, which is estimated to happen about 8 times in every 100,000 injections, can be a big deal if someone is walking out of a clinic and hits their head on concrete. In our clinic we recommend doing preteen/teen vaccines towards the beginning of the visit, so they’re sitting for 15-30 minutes afterwards. Given that most fainting is not serious, and that serious complications of fainting can be prevented by sitting after getting the shot, the possibility of fainting is not a reason to skip this vaccine.

Hundreds of studies covering millions of doses and millions of people consistently fail to identify any safety signals associated with HPV vaccines. 

The vaccine is licensed in 120 countries around the world, with ongoing monitoring of both safety and efficacy in many countries. Post-licensure surveillance data concerning the safety profiles for each of the HPV vaccine brands have detected no serious safety issues to date except rare reports of anaphylaxis. 

The World Health Organization Global Advisory Committee on Vaccine Safety (GACVS) periodically issues statements on the safety of HPV vaccine. “The GACVS has systematically investigated safety concerns raised about HPV vaccines and has issued several reports in this regard. To date, it has not found any safety issue that would alter its recommendations for the use of the vaccine.” 

Ferris D, Samakoses R, Block SL, Lazcano-Ponce E, Restrepo JA, Reisinger KS, Mehlsen J, Chatterjee A, Iversen O-E, Sings HL, Shou Q, Sausser TA, Saah A. Long-term Study of a Quadrivalent Human Papillomavirus Vaccine. Pediatrics. 18 August 2014. doi: 10.1542/peds.2013-4144. ** this study used saline placebo

Stokley S, Jeyarajah J, Yankey D, Cano M, Gee J, Roark J, Curtis RC, Markowitz L; Immunization Services Division, National Center for Immunization and Respiratory Diseases, CDC. Human papillomavirus vaccination coverage among adolescents, 2007-2013, and postlicensure vaccine safety monitoring, 2006-2014 – United States. MMWR Morb Mortal Wkly Rep. 2014 Jul 25;63(29):620-4. PubMed PMID: 25055185.

What about all the deaths reported to VAERS?

VAERS is a passive reporting database, which means the system waits for reports to be made. Anyone can report any kind of event (including sore arms, fainting, car accidents, and turning into The Hulk). These events are called “adverse events following immunization” (AEFI). They’re not necessarily side effects, because they may or may not have actually been caused by the vaccine.

Reports made to VAERS are investigated. If it seems like there is a possible relationship between the event and a vaccine, then other safety databases are studied to see if the event happens more frequently in the vaccinated group. In those databases, including the Vaccine Safety Datalink, information is collected actively, for everyone who is vaccinated, meaning the information is available for everyone who received the vaccine in that health network, not just those who had an adverse event.

Authors who go digging into VAERS and claim those adverse events as being caused by the vaccine misunderstand the purpose of VAERS. Something happening after someone received a vaccine doesn’t necessarily mean the vaccine caused it (Shimabukuro). If similar events are reported frequently, especially within a certain timeframe after the same vaccine, that increases the likelihood that the vaccine caused it. Standardized criteria are used to evaluate whether the relationship between the vaccine and the event is definite, probable, possible, unlikely or unrelated. In one study by Loughlin et al, more than half were found to be unrelated or unlikely to be related to the vaccine. Of the quarter that were found to be definitely or probably related, almost all were local reactions like redness or sore arms, or effects we already know are associated with the vaccine.

Loughlin, Anita M., Colin D. Marchant, William Adams, Elizabeth Barnett, Roger Baxter, Steve Black, Christine Casey, et al. “Causality Assessment of Adverse Events Reported to the Vaccine Adverse Event Reporting System (VAERS).” Vaccine 30, no. 50 (November 26, 2012): 7253–59. https://doi.org/10.1016/j.vaccine.2012.09.074.

Shimabukuro, Tom T., Michael Nguyen, David Martin, and Frank DeStefano. “Safety Monitoring in the Vaccine Adverse Event Reporting System (VAERS).” Vaccine 33, no. 36 (August 26, 2015): 4398–4405. https://doi.org/10.1016/j.vaccine.2015.07.035.

Why give it so young? My 12-year-old isn’t sexually active!

In the US the HPV vaccine is recommended at 11-12 years old for both boys and girls. The goal is 2-fold: get immunity in place before they are exposed to the virus, and the vaccine actually works better in this age group. Kids who get this vaccine on time only need two doses instead of three, because they have such great antibody response.

But let’s say this rationale isn’t good enough. You see the value in the vaccine — sort of, you’re still hoping your kid is one of the 15% never exposed — but you want to wait. 

Wait until when? Until they’re having sex? That might already be too late. Prevention means getting protection in place before the exposure happens.

Wait as long as possible? How do you determine when that is? Before your kid becomes sexually active. Actually, six months before they become sexually active, since they should get two doses six months apart. So, six months before your kid becomes sexually active, they need to come tell you that they’re planning to become sexually active six months from now, and this is the right time to get the vaccine.

I don’t know about you, but this does not seem like a realistic expectation for my kid.

It’s also worth noting that not all sexual activity is chosen, planned or voluntary. HPV infection shouldn’t be on the list of things to worry about after an assault.

If your kid gets this vaccine at their 11 year visit with their other vaccines, then they’ll have that protection on board for whenever they are actually exposed to the virus. That’s prevention.

The dosing schedule changed?

Contrary to the claim that vaccine manufacturers are constantly pumping more and more vaccines into the schedule, the dose schedule for HPV was changed in 2016 from three doses to two doses for kids starting the series on time. This recommendation was made after ongoing research found antibody levels just as good in those who got two doses at the right ages. It’s possible that more ongoing research will find that even one dose is effective. Not only is this great for kids who don’t want to get more shots, this is really great for low resource settings where it’s much more difficult to coordinate getting people back to the clinic two or three times (which includes plenty of settings in the US), and it’s really really great given that there’s actually a shortage of this vaccine in the world, and reducing the schedule allows more people to receive this life-saving vaccine.

What’s wrong with just doing Paps?

Paps don’t prevent HPV related cell changes or cancers. Paps are a way of detecting those changes, hopefully early enough to intervene.

HPV causes lots of trouble in areas that can’t be Pap’d, like the throat. And the anus isn’t exactly easy to Pap. And abnormal Paps need to be followed up with more Paps and potentially invasive procedures.

But fundamentally, Paps don’t prevent, just like mammograms don’t prevent breast cancer. They are screening and detection tools.

Relying on Paps is like living next to a forest, in a tent, and periodically looking around for bears, and if you see one, waiting to see if it’ll tear apart your tent, then assessing the damage and throwing out the affected parts of your camp, assuming she doesn’t kill you first, which sometimes happens. It’s good to keep a lookout, but it doesn’t prevent the bear rampaging your camp. HPV vaccine is like building a bear-resistant wall that keeps out 90% of bears. I’m going for Fort Bearless.

Does the HPV vaccine cause autoimmune conditions?

This prospective study in France enrolled females 11-25 at specialized centers and followed them for six years. They looked at the incidence of autoimmune conditions including central demyelination/multiple sclerosis (CD/MS), connective tissue disease (CTD), Guillain-Barré syndrome (GBS), type-1 diabetes (T1D), autoimmune thyroiditis (AT), and idiopathic thrombocytopenic purpura (ITP). 

They did not find any increases in auto-immune conditions.

Grimaldi-Bensouda, Lamiae, Michel Rossignol, Isabelle Koné-Paut, Alain Krivitzky, Christine Lebrun-Frenay, Johanna Clet, David Brassat, et al. “Risk of Autoimmune Diseases and Human Papilloma Virus (HPV) Vaccines: Six Years of Case-Referent Surveillance.” Journal of Autoimmunity 79 (May 1, 2017): 84–90. https://doi.org/10.1016/j.jaut.2017.01.005.

Does the HPV vaccine affect fertility?

No.

But HPV infection does affect fertility.

HPV infections can affect sperm. The infectious virion binds to the spermatozoa’s head, which causes damage to the DNA being carried by the sperm, and causes a reduction in pregnancy rates (Depuydt).

The now-retracted study that claimed that pregnancy rates were decreased by the vaccine failed to account for contraception (despite the author having access to that data). People receiving HPV vaccine generally do that in a health care setting and are likely to seek contraception simultaneously. They’re also likely to delay starting a family until after 30. The study stopped the analysis at age 29 — before when the subjects were likely to be trying for pregnancy. 

And if someone has a concerning Pap smear and cervical biopsy, the procedures done on the cervix to remove the precancerous or cancerous cells, like LEEP and conization, increase the risk of preterm birth and spontaneous abortion (miscarriage) (Bjørge).

Bjørge, Tone, Gry B. Skare, Line Bjørge, Ameli Tropé, and Stefan Lönnberg. “Adverse Pregnancy Outcomes After Treatment for Cervical Intraepithelial Neoplasia.” Obstetrics and Gynecology 128, no. 6 (2016): 1265–73. https://doi.org/10.1097/AOG.0000000000001777.

Depuydt, C. E., Ggg Donders, L. Verstraete, D. Vanden Broeck, Jfa Beert, G. Salembier, E. Bosmans, et al. “Time Has Come to Include Human Papillomavirus (HPV) Testing in Sperm Donor Banks.” Facts, Views & Vision in ObGyn 10, no. 4 (December 2018): 201–5.

But I heard the HPV vaccine causes primary ovarian insufficiency?

It can be confusing to think about a single case (a young person is diagnosed with primary ovarian insufficiency) and try to figure out what caused it for that specific person. The only way to know if the vaccine caused it is to look at big groups and see if the condition (primary ovarian insufficiency) happens more frequently in a group that’s vaccinated as compared to a group that’s not vaccinated. If the vaccine causes the condition, even rarely, a big enough group should show that.

This huge study of nearly 200,000 young women found that “no significant elevated risk of primary ovarian insufficiency after adolescent vaccination was observed in this population-based retrospective cohort study.” (Naleway, 2018)

Naleway, Allison L., Kathleen F. Mittendorf, Stephanie A. Irving, Michelle L. Henninger, Bradley Crane, Ning Smith, Matthew F. Daley, and Julianne Gee. “Primary Ovarian Insufficiency and Adolescent Vaccination.” Pediatrics 142, no. 3 (September 1, 2018): e20180943. https://doi.org/10.1542/peds.2018-0943.

What about POTS and other autonomic disorders?

It can be tempting to think that conditions that tend to occur in populations that are vaccinated are happening because of the vaccine. But these conditions would happen in this age group regardless, because they happen in that age group. Lots of conditions appear around the time of puberty, because they are hormonally driven, and puberty is when hormones ramp up.

This position statement from the American Autonomic Society finds that “there are no data to support a causal relationship between HPV vaccination and CRPS, chronic fatigue, and postural tachycardia syndrome to other forms of dysautonomia.”

Barboi, Alexandru, Christopher H. Gibbons, Felicia Axelrod, Eduardo E. Benarroch, Italo Biaggioni, Mark W. Chapleau, Gisela Chelimsky, et al. “Human Papillomavirus (HPV) Vaccine and Autonomic Disorders: A Position Statement from the American Autonomic Society.” Clinical Autonomic Research, September 2, 2019. https://doi.org/10.1007/s10286-019-00608-w.

Does the HPV vaccine give kids license to engage in risky sexual activity?

There is no link between HPV vaccine and sexual behavior. Receiving this vaccine does not make a child or teenager more likely to engage in sexual activity, or to engage in sexual activity sooner or at a younger age.

It is important to get the vaccine before someone starts engaging in sexual behavior. We want immunity in place before the person is ever exposed to HPV. The vaccine works better if someone has never been exposed to HPV before (Arbyn).

Arbyn, Marc, Lan Xu, Cindy Simoens, and Pierre PL Martin‐Hirsch. “Prophylactic Vaccination against Human Papillomaviruses to Prevent Cervical Cancer and Its Precursors.” Cochrane Database of Systematic Reviews, no. 5 (2018). https://doi.org/10.1002/14651858.CD009069.pub3.

Smith, Leah M., Jay S. Kaufman, Erin C. Strumpf, and Linda E. Lévesque. “Effect of Human Papillomavirus (HPV) Vaccination on Clinical Indicators of Sexual Behaviour among Adolescent Girls: The Ontario Grade 8 HPV Vaccine Cohort Study.” CMAJ: Canadian Medical Association Journal = Journal de l’Association Medicale Canadienne 187, no. 2 (February 3, 2015): E74–81. https://doi.org/10.1503/cmaj.140900.

If the vaccine has only been out since 2007, and these cancers take a while to develop, how do we know whether or not it really works?

This is a great question. Here’s a road map on how you get from HPV infection to cancer:

The vaccine is a roadblock on this road map. It stops that very first step: infection.

We know this vaccine works by analyzing data in phases.

1. By looking at HPV infections in general
2. By looking at pre-cancerous lesions
3. By looking at the cancers that do happen

We know the HPV vaccine prevents HPV infections in general

A 2018 study by Chaturvedi et al showed an 88% reduction in oral HPV infection rates between those who were vaccinated with at least one dose of HPV vaccine, and those who had received none. Moreover,  the investigators actually found no infections in vaccinated males, which would suggest that Gardasil may reduce the prevalence of those infections by as much as 100%.

Markowitz (2016) found that within 6 years of vaccine introduction, there was a 64% decrease in infections caused by the four relevant HPV strains among females aged 14 to 19 years and a 34% decrease among those aged 20 to 24 years. 

This 2016 meta-analysis finds “maximal reductions of approximately 90% for HPV 6/11/16/18 infection, approximately 90% for genital warts, approximately 45% for low-grade cytological cervical abnormalities, and approximately 85% for high-grade histologically proven cervical abnormalities have been reported.” (Garland)

Chaturvedi, Anil K., Barry I. Graubard, Tatevik Broutian, Robert K. L. Pickard, Zhen-Yue Tong, Weihong Xiao, Lisa Kahle, and Maura L. Gillison. “Effect of Prophylactic Human Papillomavirus (HPV) Vaccination on Oral HPV Infections Among Young Adults in the United States.” Journal of Clinical Oncology: Official Journal of the American Society of Clinical Oncology 36, no. 3 (20 2018): 262–67. https://doi.org/10.1200/JCO.2017.75.0141.

Garland, Suzanne M., Susanne K. Kjaer, Nubia Muñoz, Stan L. Block, Darron R. Brown, Mark J. DiNubile, Brianna R. Lindsay, et al. “Impact and Effectiveness of the Quadrivalent Human Papillomavirus Vaccine: A Systematic Review of 10 Years of Real-World Experience.” Clinical Infectious Diseases 63, no. 4 (August 15, 2016): 519–27. https://doi.org/10.1093/cid/ciw354.

Markowitz, Lauri E., Gui Liu, Susan Hariri, Martin Steinau, Eileen F. Dunne, and Elizabeth R. Unger. “Prevalence of HPV After Introduction of the Vaccination Program in the United States.” Pediatrics 137, no. 3 (March 1, 2016). https://doi.org/10.1542/peds.2015-1968.

We know the HPV vaccine prevents pre-cancerous lesions

A Pap smear is a screening test. It does not diagnose precancer or cancer. Only a biopsy can do that. 

From ACOG, “Squamous intraepithelial lesion (SIL) is used to describe Pap test results. “Squamous” refers to the type of cells that make up the tissue that covers the cervix. SIL is not a diagnosis of precancer or cancer. The Pap test is a screening test. It cannot tell exactly how severe the changes are in cervical cells. A cervical biopsy is needed to find out whether precancer or cancer actually is present.”

If someone goes on to have a cervical biopsy, ACOG goes on to explain that the results are described in grades of cervical intraepithelial lesions (CIN). “CIN describes the actual changes in cervical cells. CIN is graded as 1, 2, or 3. CIN 1 is used for mild (low-grade) changes in the cells that usually go away on their own without treatment. CIN 2 is used for moderate changes. CIN 3 is used for more severe (high-grade) changes. Moderate and high-grade changes can progress to cancer. For this reason, they may be described as precancer.”

In the United States, 3.5 million (7%) of the 50 million Pap tests performed each year are abnormal and require additional testing, whether a repeat Pap or a biopsy. That’s millions of procedures being done. That’s significant time and expense, not to mention potential physical pain and emotional anguish.

Abnormal results can cause significant worry, stress and anxiety, as people receive concerning results, schedule a follow up procedure, wait for the procedure, experience the procedure, then wait for the results of the procedure. Even if the biopsy is ultimately reassuring, that’s a lot to go through. And if it’s not reassuring?

Approximately 300,000 of these women are subsequently diagnosed with CIN 2 or 3. It’s important to note that biopsies and therapies that are used to remove abnormal cells are not without risks. These procedures include LEEP, which is a thin wire loop that carries electrical current to carve off abnormal areas of cervix, and conization, where a cone shaped piece of the cervix is removed. These procedures can increase the risk of spontaneous abortion (miscarriage) and preterm birth. 

While it’s great that we can detect and treat precancerous changes, it would be even better if they did not occur in the first place, did not require detection, did not require biopsy diagnosis, and did not require removal.

HPV vaccine significantly reduces the number of HPV-related procedures being performed.

A Scottish retrospective study published in 2019 looked at the likelihood of having abnormal cells found at age 20. Those who received HPV vaccine at age 12-13 were a whopping 89% less likely to be diagnosed with CIN 3 or worse (Palmer).

A Cochrane review published in 2018 (Arbyn) examined results from 26 different placebo-controlled clinical studies with over 73,000 participants. The review states:

There is high‐certainty evidence that HPV vaccines protect against cervical precancer in adolescent girls and young women aged 15 to 26. The effect is higher for lesions associated with HPV16/18 than for lesions irrespective of HPV type. The effect is greater in those who are negative for [high risk HPV] or HPV16/18 DNA at enrollment than those unselected for HPV DNA status. There is moderate‐certainty evidence that HPV vaccines reduce CIN2+ in older women who are HPV16/18 negative, but not when they are unselected by HPV DNA status.

Arbyn, see full citation below

That means that the vaccine is more effective in someone who was negative for the targeted HPV types before they were vaccinated. If they had already experienced infection, the benefit was more modest. This is why we want to vaccinate at 11-12, before sexual activity, so that the recipient is negative at the time of immunization.

Again, Garland’s 2016 meta-analysis finds reduction of “approximately 45% for low-grade cytological cervical abnormalities [CIN1], and approximately 85% for high-grade histologically proven cervical abnormalities [CIN2/3] have been reported.” This article is an excellent review of worldwide implementation of HPV vaccine programs and the research being published in dozens of countries.

The vaccine has absolutely been out long enough to know that it reduces the number of pre-cancerous lesions. If you have reduced the number of pre-cancerous lesions, then you have reduced the number of lesions in existence that could progress to cancer.

Arbyn, Marc, Lan Xu, Cindy Simoens, and Pierre PL Martin‐Hirsch. “Prophylactic Vaccination against Human Papillomaviruses to Prevent Cervical Cancer and Its Precursors.” Cochrane Database of Systematic Reviews, no. 5 (2018). https://doi.org/10.1002/14651858.CD009069.pub3.

Garland, Suzanne M., Susanne K. Kjaer, Nubia Muñoz, Stan L. Block, Darron R. Brown, Mark J. DiNubile, Brianna R. Lindsay, et al. “Impact and Effectiveness of the Quadrivalent Human Papillomavirus Vaccine: A Systematic Review of 10 Years of Real-World Experience.” Clinical Infectious Diseases 63, no. 4 (August 15, 2016): 519–27. https://doi.org/10.1093/cid/ciw354.

Palmer, Tim, Lynn Wallace, Kevin G Pollock, Kate Cuschieri, Chris Robertson, Kim Kavanagh, and Margaret Cruickshank. “Prevalence of Cervical Disease at Age 20 after Immunisation with Bivalent HPV Vaccine at Age 12-13 in Scotland: Retrospective Population Study.” The BMJ 365 (April 3, 2019). https://doi.org/10.1136/bmj.l1161.

We know the HPV vaccine prevents cervical cancer

Though cervical cancer is typically diagnosed in people 35-44, some people are diagnosed at a younger age. A study analyzing all cervical cancer cases diagnosed in people 15-24 years and tracked in the US, District of Columbia and Puerto Rico found a 29% drop after the vaccine was introduced in 2006. This decrease was statistically significant.

As more time passes, we will have more and more data that shows a reduction in actual cancer cases.

Guo, Fangjian, Leslie E. Cofie, and Abbey B. Berenson. “Cervical Cancer Incidence in Young U.S. Females After Human Papillomavirus Vaccine Introduction.” American Journal of Preventive Medicine 55, no. 2 (2018): 197–204. https://doi.org/10.1016/j.amepre.2018.03.013.

What to know: the naturopathic conclusion

HPV vaccine is older than the first iPhone. It has been licensed in 120 countries around the world. As of 2017, 74 countries had added the vaccine to their routine immunization schedules [PDF]. Hundreds and hundreds of studies show that it’s effective in preventing HPV infections and pre-cancerous lesions, and as time goes by, more and more studies are bearing out the promise of cancer reduction. The studies cited here are but a fraction of the studies that have been done on this vaccine.

Parents who are concerned about getting their child the HPV vaccine generally have been made fearful of the vaccine, and received false reassurance about the risks of HPV infections. They look at the odds of dying from cervical cancer and think, that isn’t going to happen to my kid!

But there is a lot of room for suffering between healthy and dead. This vaccine is not only about preventing death from cervical cancer. It’s about preventing treatment for cervical cancer. Preventing the treatment for pre-cancerous lesions. Preventing the procedures to screen and detect those lesions. And warts, anal cancer, throat cancer, tonsil cancer, and a host of other HPV-related ills. The vaccine is a tremendous opportunity to prevent suffering in many forms. Please take advantage of it.