This article appeared in Forbes. Read the full story here.
It’s only been a few years since researchers and public health officials determined that just two doses of the HPV vaccine, instead of three, are sufficient to protect people from the infection that can cause multiple cancers and genital warts, as long as they receive the vaccine in early adolescence. Now evidence is accumulating that suggests even one dose is enough.
A study from Australia found high levels of protection in women who received only one dose of the HPV vaccine. Past research has already conclusively shown that three doses of the HPV vaccine are highly effective in protecting against cervical cancer, and two doses are effective in those who receive the vaccine before age 15. (The vaccine is most effective in those who have not yet been exposed to any HPV strains, which is more common and likely among younger individuals.)
The possibility that just one dose is highly protective as well is encouraging, given the low rates of return for second doses and the fact that the HPV vaccine injection tends to be more painful than most other vaccines.
“If one dose could prevent pre–cancerous cervical lesions, then global cervical cancer prevention would be greatly facilitated,” wrote lead author Julia M.L. Brotherton and her colleagues in the journal Papillomavirus Research.
HPV is a virus most commonly—though not always—transmitted sexually. It’s responsible for approximately 5% of all cancers in the world, including nearly all cervical and anal cancer. About 7 of every 10 cases of head, neck and throat (oropharyngeal) cancers are caused by HPV strains as well. HPV infections also lead to a third of all penile cancers and about half of vaginal and vulvar cancers.
Though rates of cervical cancer have dropped by over 70% due to screenings, routine screening does not exist for the other cancers caused by HPV. (Some high-risk individuals or those in remission may undergo specialized screening for some of these cancers, but the general population does not.) The vaccine is therefore the most effective way to reduce risk for these cancers since the nine strains it includes represent about 90% of all HPV-caused cancers.