Why get three shots when you can just get one?
That is the potential promise being shown by a single-dose approach to the human papillomavirus (HPV), the most common sexually transmitted infection (STI), with over 3 million cases reported in the U.S. each year.
There are actually over 100 types of HPV and infection can result in low-grade lesions like warty growths on the penis, vulva, perineum, vagina, cervix, urethra, and perianal area or low-grade lesions on Pap test.
Oftentimes, the virus will fade away on its own; however, certain high-risk HPV can cause cancer. In fact, 95% of cervical cancers worldwide are caused by high-risk types of the virus. Although registries do not collect data on the presence or absence of HPV in cancer tissue at the time of diagnosis, the CDC estimates that HPV is responsible for more than 90% of anal and cervical cancers, about 70% of vaginal and vulvar cancers, around 70% of mouth and throat cancers, and more than 60% of penile cancers.
The latest news about the development of a single-dose vaccine is encouraging. Based on a trial involving young women in Kenya, the World Health Organization’s Strategic Advisory Group of Experts on Immunization (SAGE) is now recommending a one- or two-dose schedule for the primary target of girls aged 9-14; one or two-dose schedule for young women aged 15-20; and two doses with a 6-month interval for women older than 21. Immuno-compromised people should still receive three doses if possible.
(Note: The U.S. has yet to change its recommendation of three vaccinations.)
Of course, being vaccinated against HPV is highly recommended for disease prevention. In addition, “barrier method contraception” like condoms are best at preventing sexually transmitted infections. Anecdotally, over the past few years I’ve seen roughly the same amount of HPV infections, but the incidences of high-grade lesions have decreased, which is another encouraging sign.
A single-dose vaccine is likely more advantageous, being less time-consuming for patients and healthcare providers alike, and would increase patient compliance and decrease costs.
In the meantime, the CDC is the governing body that sets the standards for vaccine recommendations in the U.S. Perhaps it too will issue new HPV vaccine recommendations as a result of this study.