HPV vaccine: Preventing cervical cancer
View(s):Human papillomavirus (HPV) is a common sexually transmitted virus all over the world. Most HPV infections don’t cause any symptoms, and go away on their own. But HPV is important mainly because it can cause cervical cancer in women. Every year in Sri Lanka about 1,325 women die of cervical cancer. It is the second leading cause of cancer deaths among women around the world including Sri Lanka, the first being breast cancer.
HPV is also associated with several less common types of cancer in both men and women. It can also cause genital warts in both men and women and warts in the upper respiratory tract (back of throat including base of tongue and tonsils). Genital warts are not life-threatening. But they can cause emotional stress and their treatment can be very uncomfortable. It also can cause cancers of the anus, penis, vagina, and vulva and oropharynx.
Why get vaccinated?
Two vaccines are available to prevent the human papillomavirus (HPV) types that cause most cervical cancers. HPV vaccine is an inactivated (not live) vaccine which protects against two to four major types of HPV. These vaccines are bivalent vaccine and quadrivalent vaccine. The quadrivalent HPV vaccine also prevents HPV types that cause most genital warts. The quadrivalent vaccine also has been shown to prevent some cancers of the anus, vulva (area around the opening of the vagina), and vagina. Both vaccines are administered as three injections spread over six months.
HPV vaccine can prevent about 80% of cervical cancer and most genital warts.
Protection from HPV vaccine is expected to be long-lasting and additional booster doses are not recommended. But vaccinated women still need cervical cancer screening because the vaccine does not protect against all HPV types that cause cervical cancer.
Who should get the HPV vaccine and when?
Routine Vaccination
HPV vaccine is routinely recommended for girls between 11 to 12 years of age. The quadrivalent vaccine (the type recommended for prevention of genital warts) may also be given in three doses to boys aged nine to 26 yrs.
It is important for girls to get HPV vaccine before their first sexual contact, because they get exposed to HPV. However, if a female is already infected with a type of HPV, the vaccine will not prevent disease from that type.
Catch-Up Vaccination
The vaccine is also recommended for females 13 through 26 years of age who did not receive it when they were younger.
Will sexually active females benefit from the vaccine?
Ideally females should get the vaccine before they become sexually active and exposed to HPV. Females who are sexually active may also benefit from vaccination, but they may get less benefit. This is because they may have already been exposed to one or more of the HPV types targeted by the vaccines. However, few sexually active young women are infected with all HPV types prevented by the vaccine, so most young women could still get protection by getting vaccinated.
Can pregnant women get the vaccine?
The vaccines are not recommended for pregnant women. Studies show that HPV vaccines do not cause problems for babies born to women who were vaccinated while pregnant, but more research is still needed. A pregnant woman should not get any doses of either HPV vaccine until her pregnancy is completed.
How long does vaccine protection last?
Research suggests that vaccine protection is long-lasting.
What does the vaccine not protect against?
The vaccines do not protect against all HPV types— so they will not prevent all cases of cervical cancer. About 20% of cervical cancers will not be prevented by the vaccines, so it will be important for women to continue getting screened for cervical cancer (regular Pap smear tests). Also, the vaccines do not prevent other sexually transmitted infections (STIs).
How safe are the HPV vaccines?
Both vaccines have been licensed by the Drug Regulatory Authority of the Ministry of Health as safe and effective. Both vaccines were studied in thousands of people around the world, and these studies showed no serious safety concerns. Side effects reported in these studies were mild, including pain where the injection was given, fever, dizziness, and nausea. Vaccine safety continues to be monitored by Ministry of Health, Epidemiology unit, CDC (USA) and other global institutes. More than 46 million doses of HPV vaccine have been distributed in the United States as of June 2012.
Fainting, which can occur after any medical procedure, has also been noted after HPV vaccination. Fainting after any vaccination is more common in adolescents. Because fainting can cause falls and injuries, adolescents and adults should be seated or lying down during HPV vaccination. Sitting or lying down for about 15 minutes after a vaccination can help prevent fainting and injuries.
What about vaccinating boys and men?
Quadrivalent vaccine was found to be safe and effective for males nine -26 years. ACIP recommends routine vaccination of boys aged 11 or 12 years with 3-doses of quadrivalent vaccine. The vaccination series can be started beginning at age nine years. Vaccination is recommended for males aged 13 through 21 years who have not already been vaccinated or who have not received all three doses. The vaccine is most effective when given at younger ages; males aged 22 through 26 years may be vaccinated.
What is the cost?
The price of a dose of the HPV vaccine ranges from Rs. 3,000/- to 3,500/-
What vaccinated women need to know:
Will women who have been vaccinated still need cervical cancer screening?
Yes, vaccinated women will still need regular cervical cancer screening by Pap smear tests (PST) because the vaccines protect against most but not all HPV types that cause cervical cancer. Also, women who got the vaccine after becoming sexually active may not get the full benefit of the vaccine if they had already been exposed to HPV.
Are there other ways to prevent cervical cancer?
Regular cervical cancer screening and follow-up can prevent most cases of cervical cancer. The PST can detect cell changes in the cervix before they turn into cancer. PST can also detect most, but not all, cervical cancers at an early, treatable stage. Most women diagnosed with cervical cancer have either never had a PST, or have not had a PST in the last five years (Data from US).
Are there other ways to prevent HPV?
For those who are sexually active, condoms may lower the chances of getting HPV, if used with every sex act, from start to finish. Condoms may also lower the risk of developing HPV-related diseases (genital warts and cervical cancer). But HPV can infect areas that are not covered by a condom. People can also lower their chances of getting HPV by having a faithful relationship with one partner. However, it may not be possible to determine easily, if a partner who has been sexually active in the past is currently infected.
(The writer is a Senior Professor of Microbiology, Faculty of Medicine, Colombo and Past President, Vaccine Forum of Sri Lanka)