The federal government revised its recommendations for the Gardasil vaccine this week, saying that only two doses of the HPV vaccine are now required for protection and that the doses should be spaced farther apart than previously recommended.
The CDC previously recommended three doses of Gardasil, which is the only vaccine in the United States that is currently licensed to prevent the human papillomavirus (HPV). HPV can cause some cancers such as cervical cancer, throat cancer, and mouth cancer.
Government officials say that the change came after studies showed that two doses protected recipients for “decades,” NBC News reports. They said that earlier studies had only been performed on children who received three doses of the vaccine, so researchers had not realized that two vaccinations might be sufficient.
They also reported that they found that the vaccine was at least as effective in preventing HPV if the doses were a year apart, and perhaps even more effective. Previous recommendations had been that children should receive the second shot one to two months after the first, and the third shot six months after that.
The two original HPV vaccines offered in the United States protected against either two or four of the strains of HPV that have been linked to some cancers. Now the only vaccine available in the U.S. is Merck’s Gardasil 9, which claims to protect against nine strains of HPV.
Dr. Nancy Messonnier, director of the National Center for Immunization and Respiratory Diseases at the CDC, said that researchers still don’t know how many doses of older HPV vaccines are needed, so they are still recommending three doses for kids who were vaccinated with earlier versions of the HPV vaccine.
There are over 100 strains of HPV, according to Web MD. About 40 of these strains are sexually transmitted, and about half of all sexually active people will contract at least one strain. Symptoms are typically mild if they are experienced at all, and HPV tends to go away on its own.
Some strains of HPV can cause genital warts. These strains are considered “low risk” strains and rarely develop into cancer. The most common of these strains is now included in Gardasil 9.
HPV typically clears up on its own. In fact, research has shown that 90 percent of women who contract HPV will show no traces of infection within two years.
The CDC recommends that all preteen girls and boys receive the Gardasil vaccine starting at age 11 or 12. One reason is that this is before teens are sexually active. They also recommend vaccination at an earlier age because older teens are less likely to get health checkups than preteens.
Despite the CDC recommendations, many Americans continue to have reservations about the HPV vaccine.
Clinicians becoming reluctant to recommend HPV vaccine due to reports of serious adverse reactions https://t.co/fmSpYCSAN3— CMSRI (@CMSRIResearch) October 21, 2016
Some have responded to the new Gardasil recommendation with cynicism, noting that most teens were not getting three doses of the HPV vaccine anyway and pointing out the high cost and health concerns that have been linked to the controversial vaccine.
A 2015 study reported in the British Medical Journal found that two doses of HPV vaccination were “likely” to protect against HPV infection for at least 10 years. Researchers determined that three doses probably provided longer protection, but they did not know if it was worth the higher government cost, writing that the risk-benefit ratio was probably best for governments if only two doses were given since the vaccine is so costly for government health programs.
Researchers noted that even the WHO has switched to recommending only two doses of the HPV vaccine because of the costs.
“The World Health Organization’s Strategic Advisory Group of Experts on Immunization (SAGE) also recommended a two dose schedule for girls aged 9-14 years after reviewing evidence including cost effectiveness modelling.”
Gardasil was first approved in the United States in 2006, though it was not approved for boys and young men until 2009. The Atlantic reports that Gardasil is Merck’s top selling vaccine, bringing in $1.4 billion in annual sales.
[Featured Image by John Amis/AP Images]