HPV vaccination is reducing the incidence of abnormal cervical cell growth in women and girls in Australia. The standard three-shot regimen against sexually spread human papillomavirus nearly halves the likelihood of developing precancerous lesions on the cervix, the forerunners of cervical cancer that a Pap smear can detect.
Before these findings, reported March 4 in BMJ, there was a lot of clinical information but little real-world evidence to show that the vaccine protects against such abnormal growths. Researchers at the University of Queensland in Brisbane and elsewhere examined data on more than 108,000 girls and women age 12 to 26 who got their first Pap smear between 2007 and 2011 — after HPV mass vaccination had begun in Australia.
Those who received all three shots were 54 percent as likely as unvaccinated women to have precancerous cervical growth and two-thirds as likely to have other abnormal cervical cell growth. Getting two HPV shots conferred less protection. The findings jibe with data suggesting that the two cancer-causing virus subtypes targeted by vaccination, HPV-16 and HPV-18, account for more than half of cervical cancers. Other HPV subtypes cause the rest. Vaccination in Australia has outpaced U.S. rates (SN: 4/20/13, p. 20).
