Gardasil

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How does it work?

Gardasil is a vaccine against the human papilloma virus (HPV). This virus is a sexually-transmitted infection that can cause genital warts, pre-cancerous abnormalities of cells in the female genitals (cervix or vulva) and cervical cancer. The vaccine works by provoking the body's immune response to this virus, without actually causing HPV infection or any of the diseases.

When the body is exposed to foreign organisms, such as viruses and bacteria, the immune system produces antibodies against them. Antibodies help the body recognise and kill the foreign organisms. They then remain in the body to help protect the body against future infections with the same organism. This is known as active immunity.

The immune system produces different antibodies for each foreign organism it encounters. This establishes a pool of antibodies that helps protect the body from various different diseases.

Vaccines contain extracts or inactivated forms of bacteria or viruses that cause disease. These altered forms of the organisms stimulate the immune system to produce antibodies against them, but don't actually cause disease themselves. The antibodies produced remain in the body so that if the organism is encountered naturally, the immune system can recognise it and attack it, thus preventing it from causing disease.

Each virus or bacteria stimulates the immune system to produce a specific type of antibody. This means that different vaccines are needed to prevent different diseases.

Gardasil contains inactivated extracts from four different types of the human papilloma virus: types 6, 11, 16 and 18. HPV types 16 and 18 are responsible for approximately 70 per cent of cervical cancer cases and HPV types 6 and 11 are responsible for approximately 90 per cent of genital wart cases. Gardasil stimulates the immune system to produce antibodies against these types of the virus and is given to prevent the diseases that they can cause.

The vaccine is given by injection into the muscle of the upper arm or upper thigh. Three doses are needed and one of two schedules can be used. Either the first two doses are given two months apart and the third dose six months after the first dose, or the first two doses are given at least one month apart with the third dose at least three months after the second dose. All three doses should be given within a one year period.

At the moment it is not known exactly how long the protective effect of the vaccine will last for. Long term follow-up studies into this are ongoing.

What is it used for?

Prevention of the following diseases caused by the human papilloma virus (HPV) types 6, 11, 16, and 18:

- genital warts
- pre-cancerous abnormalities of cells in the cervix (CIN 2/3) or vulva (VIN 2/3)
- cervical cancer.

The vaccine has been shown in clinical trials to prevent these diseases in adult women aged 16 to 26 years. The vaccine has also been shown to produce antibodies against HPV in children and adolescents aged 9 to 15 years. It is not known if these antibodies will prevent HPV disease in adult males.

Warning!

- This vaccine may not provide protection against HPV in everyone who has the vaccine. It will also only provide protection against HPV types 6, 11, 16, and 18. It will not protect against any other sexually-transmitted infections. This means that after having the vaccine you should still practice safe sex and use condoms to prevent STIs.
- This vaccine should not be used as an alternative to having regular cervical smear tests. This is because no vaccine is 100 per cent effective and this vaccine will not provide protection against types of HPV that are not in the vaccine. It also won't protect you from any cancerous changes that may be caused by an HPV infection you may already have. It is important to keep having regular smear tests.
- People who have an underactive immune system, for example due to a genetic defect, disease such as HIV infection, or treatment with immunosuppressant medicines such as chemotherapy, high-dose corticosteroids, or immunosuppressants used following an organ transplant, may not produce an adequate number of antibodies in response to this vaccine. As a result, the vaccine may be less effective in these people.

Use with caution in

- People at risk of bleeding after an injection into a muscle, for example due to blood clotting disorders such as haemophilia or a reduced platelet count in the blood .

Not to be used in

- Sudden feverish illness. (The vaccine should be postponed until after recovery.)
- This vaccine is not recommended for children under nine years of age, as its safety and effectiveness have not been studied in this age group.

This medicine should not be used if you are allergic to one or any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy. If you feel you have experienced an allergic reaction, stop using this medicine and inform your doctor or pharmacist immediately.

Pregnancy and breastfeeding

Certain vaccines should not be given during pregnancy or breastfeeding. However, other vaccines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh any risks to the unborn baby. Always inform your doctor if you are pregnant or planning a pregnancy, before having any vaccine or using any medicine.

- As the safety of this vaccine during pregnancy has not been fully established, it is recommended that it is not given to pregnant women.

Instead it should be postponed until after the pregnancy is over. Seek further advice from your doctor.
- This vaccine can be given to women who are breastfeeding. It has not been shown to have any effect on a nursing infant, or to be any less effective in women who are breastfeeding.

Side effects

. This vaccine contains no live virus and so cannot cause infection with HPV or any of the diseases HPV can cause.

Vaccines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this vaccine. Because a side effect is stated here, it does not mean that all people receiving this vaccine will experience that or any side effect.

- Pain, redness or swelling at the injection site.
- Fever.
- Bleeding or itching at the injection site.
- Itchy skin rash (hives).
- Narrowing of the airways, as occurs in an asthma attack (bronchospasm).
- Nausea and vomiting.
- Dizziness.
- Fainting.

The side effects listed above may not include all of the side effects reported by the vaccine's manufacturer. For more information about any other possible risks associated with this vaccine, please read the information provided with the vaccine or consult your doctor or pharmacist.

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