Childhood HPV vaccine lowers precursor to cervical cancer 'greater than expected'
The vaccine was most effective for girls vaccinated at ages 12 to 13
"The magnitude of the effect is greater than expected," study author Dr. Tim Palmer from the University of Edinburgh told Reuters Health by email.
Receiving three doses of the vaccine at the recommended ages of 12 to 13 was associated with "a profound reduction of cervical disease seven years later," he and his colleagues report in the BMJ.
Rates of CIN were low overall. But compared with unvaccinated women, vaccinated women had:
- An 89 per cent lower rate of CIN Grade 3 or worse (0.59 per cent in unvaccinated women versus 0.06 per cent in the vaccinated group).
- An 88 per cent lower rate of CIN Grade 2 or worse (1.44 per cent versus 0.17 per cent).
- A 79 per cent lower rate of CIN Grade 1 (0.69 per cent versus 0.15 per cent).
Girls who were vaccinated at ages 12-13 got a greater benefit: the vaccine was 86 per cent effective for them, and 51 per cent effective when given at age 17.
"The findings are dramatic and document a considerable reduction in high-Grade cervical disease over time," Julia Brotherton, medical director at VCS Foundation in East Melbourne, Australia, writes in an editorial published with the study.
Scotland, which has an organized national cervical screening program, introduced a national immunization program against HPV in 2008, targeting girls aged 12 and 13, followed by a three-year catch-up program up to age 18.
Herd protection protects spread of HPV
There were an estimated 570,000 new cervical cancer cases globally in 2018, representing 6.6 per cent of all female cancers, according to the World Health Organization, with about 90 per cent of deaths from cervical cancer occurring in low- and middle-income countries.
Canada has organized cervical screening programs and introduced HPV vaccination programs in 2006. An estimated 1,550 Canadian women were diagnosed with cervical cancer in 2017, according to the Canadian Cancer Society.
In February, the WHO and cancer experts called the HPV vaccine a "critical" health tool and said access to it should be scaled up as swiftly as possible, especially in poorer countries.