There is growing evidence that the HPV vaccine can protect even young women and girls who have not been immunized.
A new government study found that human papillomavirus infections declined dramatically in vaccinated and unvaccinated adolescents and young women.
Data from a national database reveal an 88% decline in the prevalence of HPV strains targeted by the vaccine in girls aged 14 to 19 and a 81% decline in young women aged 20 to 24, compared to a previous period to 2006, when the vaccine was launched in the United States, researchers at the Center for Disease Control and Prevention reported on Thursday.
“This is really exciting,” said the study’s lead author, Dr. Hannah Rosenblum, a medical epidemiologist at the CDC. “This report shows the high effectiveness of the vaccine.”
HPV, or human papillomavirus, is the most common sexually transmitted infection in the United States, according to the CDC. There are many different types of HPV, but certain strains can cause cervical cancer in women and head, neck and penis cancer in men and anal cancer in men and women. In 2018, about 23.4 million men and 19.2 million women in the United States were infected with HPV strains linked to cancer. Most are infected in their late teens and 20s.
The CDC recommends two doses of the HPV vaccine for all girls and boys aged 11 to 12, but says the vaccine can be administered as early as 9 years of age. Data from 2019 showed that 72 percent of girls aged 13 to 17 years received one or more doses of the vaccine, said Rosenblum. And 54 percent completed the series of shots.
To take a look at the impact of the vaccine, Rosenblum and his colleagues turned to the National Health and Nutrition Examination Survey, or NHANES, an ongoing cross-sectional survey conducted by the CDCs National Center for Health Statistics, which monitors the health and nutrition of the civilian population. Demographic and HPV vaccination information was obtained during home interviews. Information on sexual behavior was obtained through computer-assisted audio self-interviews, while cervicovaginal samples collected by themselves were obtained from mobile examination centers.
The data revealed that between 2015 and 2018, among sexually active girls aged 14 to 19 who received at least one injection, the HPV strains targeted by the vaccine decreased by 97% compared to the pre-vaccine era. Among sexually active women aged 20 to 24 who received at least one injection, the HPV strains targeted by the vaccine decreased by 86% compared to the period before 2006.
Among sexually active teenagers and young women who were not vaccinated, there was also a decline compared to before 2006. Among girls aged 14 to 19, infections with the HPV strains targeted by the vaccine fell 87 percent, and among women young people aged 20 to 24 years, there was a 65% decline in infections with the HPV strains targeted by the vaccine.
“This is great news,” said Dr. Stephanie Blank, director of oncology at the Mount Sinai Health System. “When you’re doing a clinical trial, you don’t do a 10-year study. This study is giving the real impact of this vaccine. “
‘Perfect example of herd immunity’
The new study provides “proof of principle,” she said. “My main message is that more people should understand, and the more people who understand, the better it will work. This is actually a primary cancer prevention. “
Parents and young adults need to “take advantage of this phenomenal vaccine,” said Dr. Robert Ferris, director of the UPMC Hillman Cancer Center in Pittsburgh. “The vaccine can prevent cancers like the anal cancer Farrah Fawcett died of and throat cancers like the one Michael Douglas was treated for.”
“We still don’t have all the cancer results, but it shows that HPV vaccination is a tool for preventing infections and [the associated] cancers and pre-cancers, ”said Ferris.
The discovery that adolescents and young women who have not had the vaccine “have benefited from it is a perfect example of collective immunity,” said Dr. Nina Shapiro, professor of head and neck surgery at the David Geffen School of Medicine at UCLA and author of “Hype: A Doctor’s Guide to Medical Myths.”
Herd immunity occurs when a sufficient number of a population is immune to a disease, whether due to vaccination or previous illness, so that even unvaccinated individuals receive some protection, according to the CDC.
“Now that boys are also being immunized, we will begin to see a greater benefit from this vaccine for unimmunized girls,” said Shapiro. “Some parents don’t understand why you would give 12-year-olds a vaccine to prevent a sexually transmitted disease. They are comparing this to giving a 12-year-old child a condom. But this is a vaccine for cancer prevention. “