• Kayla Hui

HPV Vaccine

HPV or Human Papillomavirus is a viral infection, along with being a sexually transmitted infection, that causes skin or mucous membranes also known as warts. There are more than a hundred different varieties of human papillomavirus, and some types may lead to cancer. However while most infections do not lead to cancer HPV can cause cancer in the genital area. More specifically nearly all cervical cancers are caused by HPV infections, but it can take longer for an HPV infection to progress.

This is especially concerning since currently 79 million American have been diagnosed with HPV, and it is likely that many others may have HPV and be unaware. HPV infections are often sexually transmitted or through other forms of skin to skin contact, for this reason vaccines against HPV can help to prevent genital warts or forms of cancer.

Currently there are three vaccines available that can prevent infection and have been licensed in the United States. It is necessary to have multiple vaccines as Human Papillomavirus refers to a group of more than 200 related viruses, within which more than 40 are spread through direct sexual contact. The three vaccines that are currently approved are Gardasil 9, Gardasil, and Cervarix.

Since 2016 Gardasil 9 has been the only HPV vaccine in use in the United States. Gardasil 9 is administered in males and females from the age of nine years old. It is often given in either a three-dose or two-dose schedule. It is the only vaccine used in the United States because it prevents infection from nine HPV types. It protects against HPV types 6 and 11 which are known to cause 90% of genital warts. Gardasil 9 prevents infection from HPV types 16 and 18 which may cause about 70% of cervical cancers and possibly an ever higher percentage in other HPV related cancers. Additionally, Gardasil 9 also protects against types 31, 33, 45, 52, and 58 which are high-risk HPVs that account for an additional 10% to 20% of cervical cancers.

Gardasil 9 is a non- infectious subunit vaccine or a recombinant protein vaccine, and contains the purified L1 proteins for the nine HPV types. In the 1990s is when the National Institute of Health’s National Cancer Institute discovered proteins from the outer shell of HPV, the capsid, can form products that resemble the virus. These are called virus-like particles, or VLPs, which prompt an immune response similar to that of the virus, but VLPs are non-infectious as they do not contain genetic material. These VlPs are optimized for use in the vaccine through recombinant protein technology, this involves inserting DNA encoding an antigen, in this case the L1 proteins from the papillomaviruses capsid, that is used to stimulate an immune system.. Another example is that scientists from the National Institute of Allergy and Infectious Diseases have designed an experimental vaccine made up of virus-like particles to prevent chikungunya.

Gardasil protects against infections with types 6, 11, 16, and 18. Cervarix prevents infection in types 16 and 18 of HPV. Both vaccines are still used in some other countries. Gardasil is the predecessor to Gardasil 9 and was approved by the FDA in 2006. It is a routine 3-dose vaccination for children 11 to 12 years of age. Gardasil is also a recombinant protein vaccine.

Cervarix as stated previously prevents infection in types 16 and 18. Cervarix is also a recombinant human papillomavirus bivalent vaccine. A bivalent vaccine refers to a vaccine that works by stimulating an immune response against two different antigens. Cervarix is a bivalent vaccine as it uses the antigen of the two types of HPV that it protects against. Cervarix is a two dose vaccine for those aged 9 to 14. Those who are 15 years and above have a three-dose schedule.

Unlike most innovations that have been covered, HPV vaccines are an effective and almost fully developed innovation. Of course there are likely to be more vaccines to be produced in the future due to the wide variety of types of HPV present. The next important step of HPV vaccines is distribution throughout the world, so that hopefully HPV could be eradicated one day or become a known preventable infection. As technology improves the different cancers and complications caused by HPV will be significantly reduced.