INTRODUCTION
The human papillomavirus or HPV is one of the most common types of sexually transmitted diseases, causing more than 99% cases of cervical cancer and genital warts. HPV is a group of more than 100 types of viruses, which may cause warts or benign tumors called papillomas. Of these 100 types, over 30 types can be passed from one person to another through sexual intercourse. Persistent infection of HPV increases the risk of developing cervical cancer, the cervix is the neck of the womb. In the UK, about 3000 women are diagnosed with this type of cancer every year, while about 6 million new cases of genital HPV infection occur in the United States.
Many women will contract the HPV virus at one point in their lives. Often, HPV infections occur without any symptoms and may resolve without any treatment. Sometimes, HPV infection may even occur for years without being detected or without causing any harm.
Prevention is still better than cure, and with that, pharmaceutical companies, Merck and GSK have developed vaccines that could protect women against infections and diseases caused by HPV. Merck has introduced Gardasil in 2006, and is widely used. A new player in the market, Cervarix by GlaxoSmithKline is also gaining popularity since it was approved recently. These two vaccines are directed against specific HPV types and are indicated for specific age groups.
THE HUMAN PAPILLOMA VIRUS
Human Papilloma Virus is a sexually transmitted virus that is spread through direct skin-to-skin contact, during sexual intercourse. This virus infects the skin and the mucous membrane of the genital areas in both men and women, including the area outside the vagina called the vulva, the linings of the vagina and cervix, skin of the penis, the anus and rectum. Any kind of genital contact may cause the virus to be passed from one skin surface to another.
The risk of contracting the HPV virus is increased with the number of sexual partners. HPV infection is highly contagious. It has been estimated that about 75-80% of sexually active adults acquire genital HPV infection before the age of 50. Sex at an early age can also be a risk factor to acquiring genital HPV. Most women first become infected with the HPV virus between the age of 15 and 25.
Genital HPV infection may persist without any signs or symptoms, that a person will not be aware. However, 10-20% of patients present with symptoms that suggest HPV infection. One indicative symptom of HPV virus infection is genital warts. Genital warts take on different appearances. They can be flat or raised, pink or flesh-colored, small or large, or sometimes, they appear to look like cauliflowers. These genital warts can be seen in areas such as the cervix, vulva, scrotum, groin, penis, or anus. Genital warts can occur weeks or even months after sexual contact with an infected person. A genital wart suggests HPV infection, which also leads to cancerous abnormalities causing cancer of the cervix. This, however, takes years of persistent infections for it to develop into a cancerous growth.
There are over 100 types of HPV virus that are identified, and 40 of these types have the potential to infect the genital area through sexual contact. Two specific types of HPV virus have been associated to cause almost 90% of genital warts cases. These are HPV - 6 and HPV - 11, which are also considered as "low risk" since they have low cancer-causing potential. The HPV - 16 type is associated to be responsible for about 50% of cervical cancers, while other types such as HPV - 18, -31 and -45 account for more than 80% of cancer of the cervix. These types are called "high risk" for their ability to develop into cancerous growths.
THE HPV VACCINE
The human papilloma virus could have a major impact on a woman's life in that it exposes her to a high risk of developing one of the most common cancers in women, cancer of the cervix. In 2005, more than 250,000 women have died of cervical cancer and most of them are in developing countries. The World Health Organization has projected that there will be a rise in cervical cancer deaths by almost 25% in the next 10 years. Cervical cancer can be fatal. It is therefore important to educate women all over the world about the HPV virus and how to prevent it.
Like any other cancer, cervical cancer can be prevented with organized screening and early treatment program. As effective as they may be, these programs have been proven to be costly and difficult to implement especially in developing countries where there are very few resources. In 2006, a vaccine that protects against HPV infection was licensed. This vaccine, called Gardasil, by Merck & Co, is the first ever vaccine for infections and diseases associated to HPV virus. Gardasil targets four types of HPV, namely HPV - 6, -11, -16, and -18, the types that most commonly leads to cervical cancer. Another HPV vaccine that is yet to be licensed and is expected to be in the market soon is Cervarix. Cervarix is an HPV vaccine that targets two type of HPV, HPV- 45 and -31.
GARDASIL
Gardasil was introduced by Merck in 2006 and is the first vaccine developed against HPV infections and cervical cancer.
1. Drug Desciptions. This is a non-infectious recombinant vaccine that is prepared from the highly purified virus-like particles of the major capsid protein of HPV types 6, 11, 16 and 18. Gardasil is a sterile preparation, which when shaken, becomes a white, cloudy liquid.
2. Indications. Gardasil is indicated for women aged 9 until 26 years old, for the prevention of infections and diseases caused by the Human Papilloma Virus types 6, 11, 16 and 18. These diseases include cervical cancer, genital warts and various precancerous or dysplastic lesions.
3. Dosage. Gardasil is administered in 3 separate 0.5 ml doses. The schedule follows a 2-month interval for the 1st and 2nd dosages, and a 6-month interval for the 3rd dosage. Gardasil is administered intramuscularly, either in the deltoid region of the upper arm or in the higher area of the thigh.
4. Precautions. Individuals with bleeding disorders or weakened immune system should tell their healthcare provider before getting vaccinated. Gardasil does not guarantee a 100% protection against HPV infection, therefore, appropriate precautions against sexually transmitted disease are encouraged.
CERVARIX A new entrant in the market that is intended for the prevention of HPV infection is Cervarix. Manufactured by GlaxoSmithKline, this has recently been approved in Australia, and more and more countries are following suit, making it the vaccine of choice for HPV. IN the UK, the NHS has chosen Cervarix over Gardasil as HPV for its vaccine of choice to promote a national vaccination programme for teenage girls.
1. Drug Desciptions. Cervarix Is created using the protein L1 of the viral capsid. This vaccine contains no live virus or DNA and thus cannot infect the patient.
2. Indications. This vaccine is specifically for the prevention of diseases caused by HPV types 16 and 18. These virus types may cause precancerous cell abnormalities on the cervix and cervical cancer. This vaccine has shown to help prevent such diseases in women who are 15- 25 years old. More over, it was found out that this vaccine helps produce antibodies against HPV in girls aged 10-25 years.
3. Dosage. Cervarix vaccine is given intramuscularly in the upper arm. This vaccine comes in 3 dosages and is administered within 6 months. The first and second doses are one month apart while the third dose is at the 6 months mark from the original shot.
4. Precautions. People at risk of bleeding and who have underactive immune system should be cautious about getting vaccinated. Inform the healthcare provider about these conditions. Cervarix only provides protection against HPV types 16 and 18. It is advised that safe sex practices such as the use of condoms to prevent sexually transmitted diseases are observed.
HPV vaccines aim to protect individuals, especially women, against the sexually transmitted disease caused by Human Papilloma Virus. HPV is the major caused of cervical cancer in women and is affecting thousands all over the world. It is stressed, however, that whether or not women have been vaccinated with either Gardasil or Cervarix, yearly Pap screening for early signs of cervical cancer is a must.
