Cervical Cancer Vaccines Safe and Effective in Girls and Women

A study that examined data from more than 73,000 girls and women shows vaccines designed to prevent infection with human papillomavirus (HPV) are effective in protecting against precancerous cervical lesions in women, particularly in those vaccinated between age 15 and 26 years.

The study, conducted by the scientific network the Cochrane Review, examined 26 studies across the world over the past eight years to analyze the effect of the vaccines on all women, whether or not they had HPV when they were vaccinated. Specifically, they looked at evidence for two types of HPV vaccine: the bivalent vaccine targeting HPV16 and 18, and the quadrivalent vaccine targeting HPV16 and 18, as well as two other low-risk types of HPV that cause genital warts. In young women who did not carry the virus, they found the vaccine significantly reduced the risk of developing cervical precancer.

About 164 per 10,000 women who received a placebo went on to develop precancerous cells, compared with just two in 10,000 women who received the vaccine. Results for all women showed the vaccines reduced the risk of cervical precancer (linked to HPV16 and 18) from 341 to 157 per 10,000 women. And, the vaccines reduced the risk of any type of precancer lesions from 559 to 391 per 10,000. However, the analysis could not judge whether the vaccines had helped to prevent cervical cancer since the disease can take years to develop following HPV infection, and none of the trials has been long enough. The researchers also found a side effect rate of about 7 percent among both those who had been vaccinated and the control group.