THE SPEED at which COVID-19 vaccines ruptured the link between infections and death has put renewed focus on the miracle, and science, of inoculation. If only we had a vaccine for cancer, too, people have said.
Oh, wait, we do. And now a major study has shown just how effective it is.
In 2008, the UK began offering girls ages 12 and 13 an immunization against the human papillomavirus, which is largely sexually transmitted and the cause of nearly all cervical cancer. The vaccine was later rolled out in a catch-up program to older girls and, since 2019, to boys.
Using data from a population-based cancer registry taken from 2006 to 2019, researchers, publishing in the Lancet journal last week, found the vaccine had a dramatic effect on rates of cervical cancer, with an 87% reduction in those who were offered the vaccine at ages 12-13. (Reduction rates were lower among those who were part of the catch-up program as fewer took the vaccine and some may have already been sexually active.)
“The HPV immunization program has successfully almost eliminated cervical cancer in women born since Sept. 1, 1995,” the study concludes. Among the vaccine success stories, this one ought to be better known.
The study’s findings underscore the imperative of making these vaccines more widely available around the world, especially in developing countries. But it is also a reminder that take-up rates could still be higher in many countries, including the US — and not just among girls.
There are over 200 kinds of HPV common in humans; most are dealt with naturally by the body’s immune system, but some can cause genital warts or cancer. Nearly 40% of females are infected with HPV within two years of their first sexual activity, so there’s a pretty high chance of getting one. Vaccines can’t work after an HPV infection has occurred, however, which is why it’s so important that youngsters are vaccinated early.
HPV is generally known as a cause of cervical cancer, but it’s the culprit in many other cancers, too. In 1999, molecular epidemiologist and cancer expert Maura Gillison connected some head-and-neck cancers to HPV and sexually transmitted disease. The incidence of these cancers was rising at an alarming rate, especially among middle-aged men who had contracted HPV decades earlier. In the US from 2013 to 2017, there were more than 45,000 HPV-associated cancers each year; nearly 20,000 of those were among men.
Thanks to screening programs and the vaccine, the UK has seen a large drop in the main cancer-causing HPV types in both women and men, and also a large drop in the number of young people reporting genital warts. Since cancers develop slowly over time, the actual disease-prevention (and life-saving) benefits of the vaccine should be even higher. The vaccine’s success will likely prompt a rethinking of cervical screening programs, though it’s not clear whether a mid-life booster will be needed.
In 2020, the US Food and Drug Administration broadened the approval of Merck & Co.’s HPV vaccine, Gardasil 9 (which protects against nine different types of HPV and is also used in Britain), to include use for the prevention of oropharyngeal (throat) and other head and neck cancers. It’s now approved for use for males and females ages nine to 45, with two doses only for those vaccinated early.
And yet despite its success, just over half of US adolescents were up to date with their HPV vaccines in 2019, with only 52% of boys compared to 57% of girls (about 85% of females in the UK had both doses in 2020). As with everything in the US, rates vary dramatically by state.
HPV vaccination is a no-brainer, so why are rates so low? Explanations vary. The two- or three-shot dosing may be a deterrent for some parents. Some studies have suggested that because HPV is associated with sexual transmission, doctors and parents are more hesitant to discuss it. There are also the usual concerns about adverse effects and risks. In Britain, kids are generally offered the vaccine at school, which makes it much easier for parents to give consent and not forget to have it done.
On top of the world’s experience with COVID, the Lancet study on the HPV vaccine is another reminder of the lifesaving impact of vaccines. When science gives us a gift, we’d do well to take it.