The vaccination van parks outside the Collège Jean-Moulin at 8:15 on a Tuesday, and by lunch 94 of the school’s 118 fifth-year pupils have had their shot against the human papillomavirus, the sexually transmitted infection that causes nearly all cervical cancers and a growing share of throat cancers in men.

Three years after France began offering the HPV vaccine free in every public middle school, data released on Friday by the regional health agency for Auvergne-Rhône-Alpes showed vaccination coverage among 12-year-olds in the region had risen to 78 percent, from 41 percent in 2022. Among boys, who became eligible only in 2021, coverage rose from 29 percent to 74 percent. The national figure, which lagged behind, reached 66 percent, still short of the government’s 80 percent target for 2030 but up from a level that had made France one of the worst performers in Western Europe.

“We did not change the vaccine or the message,” said Dr. Camille Rousset, who runs the immunization program at the regional health agency. “We changed where the needle was. A parent who has to book an appointment, take an afternoon off work and sit in a waiting room with a 12-year-old has a dozen reasons to put it off. A consent form in a school bag has one.”

The campaign, modeled on programs in Australia and Scotland that have driven cervical cancer toward elimination, sends teams of nurses and doctors to every middle school in the autumn and again in the spring for the second dose. Parents receive information in six languages and a form to sign; those who decline are not contacted again. The regional cost is about 11 euros per pupil vaccinated, on top of the vaccine itself, compared with an estimated 35 euros for a visit to a family doctor.

Resistance has been quieter than officials feared. Nadia Belkacem, who teaches biology at a school in the Vénissieux suburb and coordinates the program there, said the questions from parents were practical rather than ideological. “They want to know whether it hurts and whether their son really needs it,” she said. “When we explain that boys get throat cancer too, and that the shot protects their future partners, most sign.” A few parents, she said, objected on religious grounds or cited misinformation seen online; her school’s refusal rate was 9 percent.

Thierry Lacombe, a father of twins at a school in the city’s sixth arrondissement, said he had intended to have his children vaccinated for two years. “I am a pharmacist’s husband. I knew all the arguments,” he said. “It still took the school doing it for me to get it done.”

The health ministry said it would extend the school model next year to a catch-up campaign for meningococcal B vaccination and was studying whether seasonal flu shots could be offered the same way. Dr. Rousset said the lesson went beyond HPV. “France has spent 20 years trying to persuade people,” she said. “It turns out a lot of them were persuaded. They just needed somebody to come to them.”