Last updated on August 24th, 2020 at 02:12 pm
Recently, a new large meta-review has been published that shows the HPV vaccine prevents infection by HPV types that are linked to genital warts which probably means it can prevent the other HPV types that are linked to several cancers. So, if we can prevent these genital warts, we probably can prevent HPV-related cancers.
This article will take a look at why the HPV vaccine is so important and review this review on how the HPV vaccine can prevent genital warts.
All about HPV and HPV vaccines
I know I add this section to every article I write about HPV vaccines. It is updated almost every time with additional information about HPV or the vaccine. Moreover, there are readers who want to know more about HPV, and this section can help someone get up-to-speed quickly.
Genital and oral human papillomavirus (HPV) infections are the most common sexually transmitted infections (STI) in the USA. HPV is generally transmitted from personal contact during vaginal, anal or oral sex.
It’s important to note that there are more than 150 strains or subtypes of HPV that can infect humans – however, only 40 of these strains are linked to one or more different cancers. Of those 40 strain, most are fairly rare.
Although the early symptoms of HPV infections aren’t serious and many HPV infections resolve themselves without long-term harm, HPV infections are causally linked to many types of cancers in men and women. According to current medical research, here are some of the cancers that are linked to HPV:
In addition, there is some evidence that HPV infections are causally linked to skin and prostate cancers. The link to skin cancer is still preliminary, but there is much stronger evidence that HPV is linked to many prostate cancers.
HPV is believed to cause nearly 5% of all new cancers across the world, making it almost as dangerous as tobacco in that respect. According to the CDC, roughly 79 million Americans are infected with HPV – approximately 14 million Americans contract a new HPV every year. Most individuals don’t even know they have the infection until the onset of cancer. The CDC also states that over 43,000 HPV-related cancers are diagnosed in the USA every year. It may be several times that amount worldwide.
There were two HPV vaccines on the world market before 2014. GSK, also known as GlaxoSmithKline, produced Cervarix, a bivalent (protects against two HPV strains) vaccine. It has been withdrawn from the US market (although available in many other markets), because of the competition from the quadrivalent (immunizes against four different HPV strains) and 9-valent (against nine HPV strains) Gardasil vaccines.
Merck manufactures Gardasil, probably the most popular HPV vaccine in the world. The first version of the vaccine, quadrivalent Gardasil, targets the two HPV genotypes known to cause about 70% of cervical cancer and two other HPV genotypes that cause genital warts. In Europe and other markets, Gardasil is known as Silgard.
The newer Gardasil 9, approved by the FDA in 2014, is a 9-valent vaccine, protecting against HPV Types 6, 11, 16, 18, 31, 33, 45, 52, and 58. It targets the four HPV strains found in the quadrivalent version, along with five additional ones that are linked to cervical and other HPV-related cancers. Both versions of Gardasil are prophylactic, meant to be given to females or males before they become exposed to possible HPV infection through intimate contact.
Gardasil is one of the easiest and best ways to prevent a few dangerous and, to abuse the definition slightly, common cancers that afflict men and women. Without a doubt, the HPV vaccine prevents cancer.
Currently, in the United States, the Advisory Committee on Immunization Practices (ACIP) recommends that preteen girls and boys aged 11 or 12 are vaccinated against HPV. The immunization is also recommended for teenage girls and young women up to the age of 26 who did not receive it when they were younger, and teenage boys and young men up to the age of 21.
Let me sum this all up so that if you come away from this section with nothing else, you get this summary. HPV is a sexually transmitted disease. HPV causes 43,000 cancers a year in the USA alone. The HPV vaccine prevents becoming infected by HPV, which means you are protected from these cancers.
The HPV vaccine prevents genital warts meta-review
On 28 May 2020, BMC Public Health published a meta-review that found that the quadrivalent HPV vaccine (see Note 1) can prevent genital warts in healthy women and men. The researchers concluded that HPV vaccines should be or continue to be included in routine immunization programs for teens and young adults.
The meta-review include eight randomized clinical trials where HPV or placebos were administered to females or males (in one of the studies). The researchers then compared the number of genital warts cases was compared between the two groups.
The researchers also reviewed eight time-trend studies to assess the population-level effect of Gardasil vaccination by comparing the rate of genital warts between pre- and post-vaccination periods. In this part of the analysis, the researchers found that:
- The HPV vaccine was found to significantly reduce the overall risk of genital warts.
- The risk of genital warts in women was substantially lower in the vaccinated group.
- Although young men were not vaccinated in this study (part of the study period pre-dated the approval for the disease in young men), the risk of genital warts was reduced in men, probably as a result of indirect protection provided by the vaccination of young women.
- The analysis showed that genital warts was reduced in those under 21 years of age compared to older persons, probably since the vaccine has only been available for around 10 years.
These results are consistent with many other systematic reviews and meta-analyses that also found that the risk of genital warts was much lower in vaccinated girls.
An Australian study has shown that genital warts have nearly disappeared from the country after 10 years of the HPV vaccine being a part of the national vaccination program. It was introduced in 2007 for 12- and 13-year-old girls.
The authors concluded:
The results from RCTs and time-trend analyses – representing more than 13,000 000 participants – have shown that the quadrivalent HPV vaccine is highly effective in preventing HPV 6/11 related GW both in women and men which gives an additional value to the application of this type of vaccine. Our meta-analysis provides up-to-date information for the public about the effectiveness of HPV vaccination. Teenagers and their parents should acquire better knowledge about HPV infection and prevention. This is of very high importance, because rumours about vaccine safety have been one of the principal obstacles for the acceptance of HPV vaccination by the public. Despite the early implementation of national vaccination programs, in the majority of developed countries coverage rates remain unsatisfactory [41].
Furthermore, the present work provides reliable information for obstetrician–gynaecologists and other health care providers who should raise the attention of parents and patients for the benefits of HPV vaccination and offer HPV vaccines. Additionally, our results demonstrating strong evidence of quadrivalent HPV vaccine effectiveness can help the governments for making decisions about the implementation of the vaccination. It would be recommended to include the quadrivalent HPV vaccine in routine immunization programme because of its high effectiveness not only against cancer but also against GW.
In summary, our results clearly show that the ecological impact of the quadrivalent HPV vaccine is high and its introduction in many countries is strongly suggested.
Summary
Once again, we have evidence in a 13 million person study that the HPV vaccine is effective. It prevents genital warts which may indicate that it also prevents other HPV infections, like the ones linked to cancers.
Get the HPV vaccine. Prevent cancer.
Notes
- The quadrivalent HPV vaccine targeted HPV types 16 and 18, which are linked to about 80% of HPV-related cancers, and HPV types 6 and 11, which are linked to 95% of genital warts cases. The quadrivalent HPV vaccine has been replaced with 9-valent Gardasil9 which targets additional HPV types that are linked to HPV-related cancers and genital warts.
Citations
- Lukács A, Máté Z, Farkas N, Mikó A, Tenk J, Hegyi P, Németh B, Czumbel LM, Wuttapon S, Kiss I, Gyöngyi Z, Varga G, Rumbus Z, Szabó A. The quadrivalent HPV vaccine is protective against genital warts: a meta-analysis. BMC Public Health. 2020 May 28;20(1):691. doi: 10.1186/s12889-020-08753-y. PMID: 32460747; PMCID: PMC7254696.
- Patel C, Brotherton JM, Pillsbury A, Jayasinghe S, Donovan B, Macartney K, Marshall H. The impact of 10 years of human papillomavirus (HPV) vaccination in Australia: what additional disease burden will a nonavalent vaccine prevent? Euro Surveill. 2018 Oct;23(41):1700737. doi: 10.2807/1560-7917.ES.2018.23.41.1700737. PMID: 30326995; PMCID: PMC6194907.
