Gardasil

Gardasil is a quadrivalent cervical cancer vaccine manufactured by Merck & Co. As well as protecting against HPV 16 and 18 that cause cancerous cells, it helps guard against HPV 6 and 11 which cause 90 per cent of genital warts.

Unlike Cervarix, Gardasil has been tested in males and can be used to effectively to prevent genital warts.

What’s in the vaccine?

·         Human Papillomavirus Type 6, 11, 16 and 18 L1 protein

·         amorphous aluminium hydroxyphosphate sulphate (adjuvant)

How does it work?

As with Cervarix, Gardasil’s active ingredient is also an inactive form of the L1 capsid protein virus-like particles (VLP) that resemble the attacking virus. Antibodies against HPV 6, 11, 16 and 18 are then triggered and remain in the body to protect against the perceived infection.

DNA Recombinant technology is used to manufacture VLPs in Saccharomyces cerevisiae (yeast). The genes coding for the L1 capsid proteins are inserted into the yeast genome. When the yeast is grown, many copies of the L1 protein-coding gene are made. The consequent proteins trigger the antibody response but as the yeast genome doesn't include the invading viral DNA, no disease can be caused.

How is it administered?

For complete immunisation, 3 doses are required, each 0.5ml. Following the initial injection, the second and third are at 2 months and 6 months respectively. Gardasil can be injected into the muscle of the upper arm or thigh.

Clinical Trial

The vaccine has been tested on thousands of females. Subjects given the vaccine as opposed to the placebo, showed significantly lower occurrence of Cervical Interepithelial Neoplasia that arose due to HPV infection.

In a group previously unexposed to HPV, the vaccine was 93-98% effective in preventing cervical cancer and genital warts.

Side Effects

As with Cervarix there are some side effects including pain and swelling around the injection site, headaches, nausea, mild fever and sore muscles. Signs of a more adverse reaction are severe stomach pains, chest pain, confusion, fainting and unusual bruising, amongst others.

Gardasil vial image courtesy of Jan Christian via Wikimedia Commons. Licensed under creative commons.