Just 1 dose of the HPV vaccine may protect against infection, new study suggests

A single dose of the human papillomavirus, or HPV, vaccine may be just as effective as two or three doses at preventing cancer-causing HPV infection, a new study suggests.

The study, published in the medical journal JAMA Network Open on Friday, found that compared with unvaccinated women, infection with certain high-risk HPV types was significantly less prevalent among women who received one, two or three doses of HPV vaccine.

The study involved analyzing data from the National Health and Nutritional Examination Survey on 1,620 women in the United States ages 18 to 26. The researchers took a close look at HPV vaccination rates and HPV infection among the women between 2009 and 2016.

The study found that 111 of the 1,004 unvaccinated women were diagnosed with infections of HPV types 6, 11, 16 or 18 between 2009 and 2016.

Yet only four of the 106 women vaccinated with one dose; seven of the 126 women vaccinated with two doses; and 14 of the 384 women vaccinated with three doses were diagnosed with those infections during that time period.

“Our study suggests that US women who received 1 dose of the HPV vaccine may have gained similar protection against vaccine-type infections compared with those who received additional doses,” the researchers wrote in the study. “These findings support previous observational studies and post hoc analyses of vaccine trials that demonstrated comparable effectiveness of 1 dose to 2 or 3 doses.”

HPV is a group of more than 200 related viruses, which can spread through sexual contact. In some cases, HPV infection can lead to six types of cancer: cervical, anal, penile, vaginal, vulvar and oropharyngeal (mouth and throat).

“HPV vaccine coverage is less than 10% globally because of poor vaccine uptake rates in many resource-limited countries. Ensuring boys and girls receive their first dose is a big challenge in several countries and a majority of adolescents are not able to complete the recommended series due to a lack of intensive infrastructure needed to administer two or three doses,” the study’s senior author, Ashish Deshmukh, an assistant professor at the University of Texas Health Science Center at Houston’s School of Public, said in a press release on Friday.

“If ongoing clinical trials provide evidence regarding sustained benefits of a one-dose regimen, then implications of single-dose strategy could be substantial for reducing the burden of these cancers globally,” he said.

The vaccine can protect against certain cancers since it works by preventing HPV infection.

It’s estimated that about 80% of people will get an HPV infection in their lifetime. While most HPV infections don’t cause cancer, high-risk HPV infections that persist can cause cancer and roughly half of infections are with a high-risk type, according to the US Centers for Disease Control and Prevention.

In June, actress and “Desperate Housewives” star Marcia Cross opened up about her battle with anal cancer. Cross, 57, revealed her diagnosis in a series of Instagram photos in 2018. Her husband, Tom Mahoney, was diagnosed with throat cancer in 2009. Doctors now suspect that Cross’ cancer and Mahoney’s came from the same type of HPV.

Cross said at the time she planned to get her 12-year-old twin daughters vaccinated. The actress told CNN she cares deeply about being able to “educate the public about HPV.”

“In spite of the optics, I care deeply about saving lives,” Cross previously wrote in an email to CNN. “To that end, the important thing to do is to educate the public about HPV. It is so common that nearly every person who is sexually active will get it at some point in their lifetime. HPV can cause cervical and other cancers …. It can take years, even decades to develop.”

The CDC currently recommends two doses of the HPV vaccine for boys and girls ages 11 and 12. The first dose is recommended around those ages and the second is recommended six to 12 months after the first dose. Children who start the vaccine series on or after their 15th birthday need three shots over six months, according to the CDC.