Does Gardasil or Cervarix Have A Better Dosing Schedule?One of the first questions people often ask about HPV vaccination is how many times they need to get the HPV jab and when they need to get them. Both currently available vaccines require a series of three shots. Gardasil is given at 0, 2, and 6 months, while Cervarix is given at 0, 1 and 6 months. In either case, you'll be done within half a year. However, it is very important to get all three shots for the HPV vaccines to have maximum efficacy.
What HPV Strains Do The HPV Vaccines Protect Against?Gardasil is designed to protect against new infections with HPV 6, 11, 16, and 18.
Cervarix is designed to protect against new infections with HPV 16 and 18.
There is also preliminary data suggesting that both HPV vaccines may offer cross-protection against other HPV strains; however, they do not protect against strains with which you have already been infected.
Are The HPV Vaccines FDA-Approved?As of 1/15/2011, Cervarix is approved for girls and women aged 10 to 25 for the prevention of cervical cancer and cervical interepithelial neoplasia.
Gardasil is approved for both men and women from the ages of 9 to 26 for the prevention of genital warts, anal cancers, and anal interepithelial neoplasias. It is also approved for the prevention of cervical cancer and cervical and vulvar interepithelial neoplasia in young women.
Neither vaccine has yet been shown to protect against diseases caused by pre-existing HPV infections.
Do Either Gardasil or Cervarix Have Safety Issues and/or Side EffectsOne of the issues that often comes up in discussions of the HPV vaccines is whether or not they're safe. Both vaccines do cause mild to moderate side effects -- such as pain and redness at the injection site, as well as headaches, stomach aches, and other full-body symptoms -- in a reasonable fraction of recipients. However, they are generally considered to be quite safe.
The more serious side effects that have been reported to the vaccine adverse event reporting system have, by and large, not been shown to be vaccine-related, and the reports of vaccine-linked fatalities appear to be unfounded.
Accessing the HPV VaccineAlthough the vaccine will not be covered by your insurance, it is possible to find doctors willing to give you the vaccine even if you are outside the currently approved age range. However, since most sexually active people will have been exposed to numerous strains of HPV by the time they are in their late 20s, there are debates over whether vaccination is actually worthwhile for these adults. If you are over 26 and considering vaccination, you should discuss your interest and your risk factors with your doctor to see if vaccination is a good choice for you.
What Antigens Do The HPV Vaccines Use?Gardasil and Cervarix each target the HPV L1 capsid protein to attempt to induce immunity against the virus. In both cases, the antigen in the vaccine is actually a virus-like particle (VLP) made up of these proteins -- or more accurately multiple VLPs, one for each strain of the virus the vaccine targets. The L1 capsid protein is a protein found on the surface of the human papillomavirus, and it varies slightly from strain to strain.
The main difference between the two vaccines is that Gardasil has 4 types of VLP instead of 2. Neither vaccine contains viral DNA and so there is no way for them to cause HPV.
What Adjuvants Do Cervarix and Gardasil Contain?The adjuvant is the carrier used to stimulate the body to produce an immune reaction against the antigen found in the vaccine. Cervarix uses the AS04 adjuvant, which is is composed of 3-O-desacyl-4’-monophosphoryl lipid A (MPL) adsorbed onto aluminum (as hydroxide salt). Gardasil uses amorphous aluminum hydroxyphosphate sulfate as an adjuvant.
Cervarix Prescribing Information. Accessed online on 1/12/2011.
Gardasil prescribing Information. Accessed online on 1/12/2011.
Jenkins(2008) A review of cross-protection against oncogenic HPV by an HPV-16/18 AS04-adjuvanted cervical cancer vaccine[...] Gynecol Oncol.110(3 Suppl 1):S18-25.
McCormack & Joura (2010) Quadrivalent human papillomavirus (types 6, 11, 16, 18) recombinant vaccine (Gardasil®): a review of its use [...]. Drugs. 70(18):2449-74.