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  • HPV is the most common sexually transmitted infection in the U.S.
  • Getting the HPV vaccine can significantly decrease the risk of developing the disease.
  • Currently, the HPV vaccine is given as a three-dose regimen.
  • A new study finds that the vaccine may be effective after a single dose.

A single dose vaccine may be highly effective in preventing human papillomavirus (HPV), according to newly published research. HPV is the most common sexually transmitted infection in the United States, according to the Centers for Disease Control and Prevention (CDC), and certain strains of the virus can lead to cervical cancer. Currently, the standard for HPV prevention is a three-dose vaccine regimen.

But now, researchers find a single-dose vaccine may be enough.

A randomized controlled trial of 2,275 women in Kenya showed that a single dose of the HPV vaccine was highly effective. According to the investigators in the trial, the results could help the WHO reach its goal of having 90 percent of 15-year-old girls vaccinated against HPV by 2030, up from the current statistic of 15 percent of women worldwide vaccinated.

HPV is the most common sexually transmitted infection in the United States. According to the CDC, approximately 43 million people had HPV in 2018, mostly those in their late teens and early 20s. There are many different strains of the HPV virus, and the majority of the strains clear up on their own within two years without causing any other health problems. However, some strains are more serious than others and can contribute to more serious conditions, including genital warts and cancers.

HPV is spread through vaginal, anal, or oral sex with someone who has the virus. The virus can be spread even when someone does not have any symptoms. Symptoms of the virus can also develop years after a person was exposed to the virus, which makes it incredibly difficult to determine when a person contracted the disease.

While the majority of HPV can clear up on its own, certain HPV can cause cervical and other cancers, like cancer of the vulva, vagina, penis, anus, and throat. Unfortunately, there is no way to know who will develop cancer from HPV.

The current regimen for the HPV vaccine is a series of three shots. The three-dose series can protect against multiple strains of HPV that cause most HPV cancers.

The vaccine is recommended for both boys and girls as early as 12 years old and for adults by the age 26. Adults aged 27 to 45 interested in getting the vaccine can talk with their clinician if it is the right choice for them.

Since the HPV vaccine was recommended in 2006, the CDC found there was a significant drop in genital warts and cervical precancers detected. Additionally, a type of HPV case called quadrivalent HPV infections decreased by 86 percent in female teens aged 14 to 19 years and 71 percent in women in their early 20s.

The study showed that after 18 months, the bivalent vaccine was 97.5 percent effective against HPV 16/18 (the HPV that causes cervical cancer). The nonavalent vaccine that protects against nine strains of HPV was 89 percent effective after 18 months. This is promising news, but more studies will have to be done to see how the vaccine holds up over time.

“The study shows efficacy from one dose of the vaccine. High antibody levels were found at 18 months. Ongoing studies are needed to find antibody levels at five years, 10 years, and 20 years. It is important to know the length of efficacy given to very young teens,” said Dr. Jennifer Wu, OB/GYN at Lenox Hill Hospital in New York, NY.

While the HPV vaccine has been effective at lowering the risk of certain cancers associated with HPV, the vaccine has not been widely adopted globally.

The global immunization coverage for HPV is just 12 percent, according to a 2021 study.

“HPV vaccines are a powerful tool to reduce cervical cancer, but too many women and girls in low- and middle-income countries don’t have access to them,” Dr. Peter Dull, deputy director of vaccine development and surveillance at the Bill & Melinda Gates Foundation, said in a statement. The Bill & Melinda Gates Foundation funded the study.

One issue may be that people need three doses to be fully protected.

The need for three doses may make it difficult for people in low- and middle-income countries where medical care may not be widely accessible. In general, some people will not return three different times to complete the regimen, meaning they are not fully protected.

Wu pointed out that protecting against HPV 16/18 in a single shot could have major consequences in decreasing cancer cases.

“Even in our own country, some patients will miss appointments for some of the HPV vaccine doses. For people in some countries with fewer resources, the vaccine would be too expensive and the travel to obtain the vaccine prohibitive,” said Wu.

Dr. Dana Bryant, a board-certified OB/GYN with White Plains Hospital Physician Associates in the New York Metro Area, said decreasing the number of vaccine doses would also decrease vaccination costs.

“A single dose vaccine would decrease costs and increase compliance among patients. Medication and vaccination compliance have been studied for decades,” said Bryant. ” It is well-known that as medication and/or vaccination doses increase, patient compliance decreases. In other words, the more doses that are required make it harder for people to comply with taking their medication or receiving the recommended vaccination.”