More than a decade ago, Britain set out to vaccinate girls ages 12 and 13 against the human papillomavirus, or HPV, which can cause cervical cancer, among other ailments.

Researchers have now observed that those shots led cases of cervical cancer to plummet among the cohort once they reached their 20s, when the risk of developing the disease is among the highest.

A study published Wednesday in medical journal the Lancet found that the HPV vaccine cut cervical cancer rates by 87 percent. Those vaccinated between the ages of 14 and 16 reported a 62 percent reduction, and those between 16 and 18 had a 24 percent lower chance compared with the unvaccinated.

“This is really exciting, as it’s the first time we’ve been able to see the real-world impact of the U.K. vaccination program,” said Sophia Lowes, health information manager at Cancer Research UK. The London-based charity funded the study conducted along with the British government and researchers at King’s College London.

The study followed the outcome of the Cervarix vaccine, which became available in Britain in 2008 and covers two main cancer-causing HPV strains. A newer HPV vaccine, called Gardasil, protects against more strains of the cancer-causing virus, and Britain switched to that version in 2012.

Starting in 2019, Britain’s National Health Service (NHS) also began offering HPV vaccines to children of all genders ages 11 to 13, as well as to adults who identify as male and have sex with other men, Lowes said.

Part of the program’s success, Lowes said, was the use of schools as vaccination sites and public health messaging to combat stigma around HPV.

“We now have over a decade of evidence to show that there aren’t any major side effects” from the vaccine, she said.

Many people over the course of their lives become infected with and fight off HPV without any complications. In the United States, it’s the most commonly sexually transmitted infection, according to the U.S. Centers for Disease Control and Prevention.

For a subset of people, however, over time the virus can cause cancer in the cervix as well as in other parts of the body, such as male genitals, the mouth and throat.

“If you notice anything that’s not normal for you, tell your doctor,” she said. “In most cases it won’t be cancer. But if it is cancer, finding it at an early stage can make a real difference.”

In January, the U.S. Department of Health and Human Services announced its own campaign to increase HPV vaccine uptake: Just less than half of young people in the United States have taken it, and 22 percent have completed the required cycle of doses, according to the agency. (Typically two to three doses of the vaccine are required, depending on the person’s age and the gap between shots.)

HPV yearly causes close to 36,000 cancer cases in people of all genders in the United States, according to the CDC.

Last November, the World Health Organization (WHO) launched an effort to eliminate cervical cancer as a public health problem. The program set an ambitious goal for countries to vaccinate 90 percent of girls by 2030 and to have 70 percent of women screened for cervical cancer by age 35.

That same month, a WHO report found that 57 percent of member states included the HPV vaccine in routine national immunization schedules. Though the WHO found there was high interest “across all income groups” in the vaccine, the sharp increase in demand coupled with issues such as supply constraints “has resulted in a slower introduction pace than desired,” the report found.

The WHO predicted that by 2024 supply shortages would be resolved and production capacity would increase.