Cervical cancer is the second most common cancer in women worldwide and the most common cancer in Indian women. Human papilloma virus (HPV), a sexually transmitted infection is the single most important contributing factor resposible for cancer cervix. The infection does not cause symptoms and condoms do notoffer protection against it. Of the various strains, HPV serotypes 16 and 18 account for nearly 76.7% of cervical cancer in India; others strains lead to genital warts. About 80% of the sexually active women acquire genital HPV by 50 years of age. A vast majority of the infections resolve spontaneously and only a minority (<1%) progress to cancer. As the lag period between the oncogenic (cancer causing) HPV infection and cervical cancer is 15–20 years, developing a vaccine against HPV was a logical, much needed step in the prevention of cervical cancer. The HPV virus cause changes in pap smear ranging from low to high-grade precancerous lesions that finally end up in cancer cervix. Regular Pap smear is essential for all sexually active women even if they have been fully vaccinated. This is because other factors too contribute to the development of cervical cancer. These include:
- Long-term use of hormonal contraceptives,
- High parity
- Early initiation of sexual activity,
- Multiple sex partners,
- Tobacco smoking
- Co-infection with chlamydia trachomatis and herpes
- Low socioeconomic status,
- Poor local hygiene
HPV vaccine induces a strong protective immune response, preventing the virus from releasing its genetic material. The two vaccines licensed globally, Gardasil and Cervarix are freely available in India. They do not protect against the strain the patient is already infected with hence, the ideal time to vaccinate a girl is before she has made her sexual debut, the recommended age for initiation of vaccination being 9–12 years. Catch-up vaccination is permitted up to the age of 26 years. A total of three doses at 0, 2 and 6 months are recommended with Gardasil and 0, 1 and 6 months with Cervarix. HPV vaccines can be given simultaneously with other vaccines such as Hepatitis B. Follow-up studies over 4–5 years showed no evidence of waning immunity and no booster is required. If the HPV vaccine schedule is interrupted, the vaccine series need not to be restarted. If the series is interrupted after the first dose, the second dose should be administered as soon as possible, with an interval of at least 12 weeks between the second and third doses. If only the third dose is delayed, it should be administered as soon as possible.
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The vaccine is administered in the lying down position and the patient should be observed for 15 min for the rare possiblity of a fainting attack. Side effects could take the form of mild to moderate pain, swelling, redness at the site of injection. The vaccine should be deferred in patients with moderate or severe acute illnesses. It is not recommended in pregnant women though feeding mothers can receive it.