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Vaccine update 2010: Keeping up with the changes

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Human papillomavirus vaccination for girls age 11–12

HPV is sexually transmitted and causes genital warts, cervical cancer, and other oral, anal, and genital cancers.

HPV is the most common sexually transmitted infection in the United States, with over 6 million new cases each year.13 A study in 2003 to 2004 using HPV DNA typing of cervicovaginal swab specimens in a sample of women between the ages of 14 and 59 found an overall point prevalence of 26.8% of any HPV type.14 Those between 20 and 24 years had the highest prevalence at 44.8%. Those ages 14 to 19 had a prevalence of 24.5%. Several studies have reported a similar age-related increase in HPV prevalence.15,16

One survey found that nearly 25% of girls in the United States are sexually active by age 15, 40% by age 16, and 70% by age 18.17 The 2005 Behavioral Risk Survey found that nearly 4% of girls were sexually active before age 13, and by the ninth grade 5.7% of those who were sexually active had had four or more partners.18 To receive the full benefit from the HPV vaccine, it should be given before this risk of acquiring HPV occurs.

A quadrivalent HPV vaccine (HPV4) was first licensed in the United States in 2006 for use in girls and women 9 to 26 years old to prevent cervical, vulvar, and vaginal precancerous lesions and cancer, and for prevention of anogenital warts. It contains viral proteins from HPV types 6, 11, 16, and 18, the types currently responsible for 70% of cervical cancers and 90% of anogenital warts. The vaccine is prepared in a yeast substrate and contains an aluminum-based adjuvant.

HPV4 has proven highly effective in women ages 16 to 26 not previously exposed to the four HPV types in the vaccine. The end points used in these studies were cervical intraepithelial neoplasia grade 2 or 3, adenocarcinoma in situ, anogenital warts, and vulvar and vaginal intraepithelial neoplasms.13,19,20 The vaccine’s effectiveness has been 98% to 100% after 3 to 5 years. These trials are ongoing.

The vaccine’s efficacy in women with current or past HPV infection is less certain. Studies of this question have included only small numbers, and the confidence intervals are large and include 0. In intention-to-treat studies, its efficacy has been 39% to 46% for prevention of cervical intraepithelial neoplasia grade 2 or 3 or adenocarcinoma in situ caused by HPV-16 or HPV-18, 69% for prevention of HPV-16- or HPV-18-related vaginal intraepithelial neoplasia, and 68.5% for vaccine-type-related warts.13

The most common adverse effects of HPV4 have included redness, pain, and swelling at the injection site, which occur in about 20% of recipients.13 There is an increased risk of syncope immediately after the vaccine is given, and observation for 15 minutes after injection is recommended. A recent study suggested a link between the vaccine and venous thromboembolism. 21 The rate was 2 per million doses, and because many of the recipients also were taking oral contraceptives, their venous thromboembolism has not yet been definitively proven to be caused by the vaccine.

HPV4 is contraindicated in those who have experienced a severe allergic reaction to a previous dose or who have an allergy to a vaccine component. Vaccination should be deferred in those with moderate or severe acute illnesses.

In June 2006, the ACIP13 made the following recommendations for HPV4:

  • Girls ages 11 to 12 years should be routinely vaccinated with three doses
  • The series can start as early as age 9 years
  • Women and girls age 13 to 26 who have not been previously vaccinated should receive catch-up vaccination
  • Neither Papanicolaou (Pap) testing nor HPV screening is necessary before vaccination
  • HPV4 can be given with other age-appropriate vaccines
  • Vaccination does not change the recommendations for cervical cancer screening
  • The recommendations remain the same regardless of abnormal Pap tests, positive HPV DNA tests, or warts.

There have been two very recent developments regarding HPV vaccines.

A bivalent vaccine (HPV2) has been licensed in the United States and approved for use in girls and women ages 10 to 25 for prevention of cervical cancer and precancerous lesions. It contains antigens against HPV-16 and HPV-18 but does not provide protection against genital warts. The ACIP has stated no preference for the bivalent or the quadrivalent vaccine for the prevention of cervical cancer and precancerous lesions.

HPV4 has also gained licensure for use in boys and men age 9 to 26 for the prevention of genital warts. The ACIP has not recommended it for routine use, leaving the decision to patients and physicians after weighing the potential benefits and costs.

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