More than 100 girls in St Helens were not fully vaccinated against the potentially cancer-causing HPV virus last year, new figures show.
Girls in England are offered free HPV jabs at school during Years 8 and 9, when they are aged between 12 and 14.
Public Health England figures show 89.1% of girls in St Helens were given the recommended two doses of the vaccine by the end of Year 9 in 2018-19.
This was above the national average, but 103 girls were still left unprotected.
The HPV vaccination protects against the human papilloma virus, which is responsible for more than 99% of cervical cancer cases as well as some other rarer cancers.
According to the NHS, the vaccine works best when girls receive it before they become sexually active.
HPV can be spread through any kind of skin-to-skin contact, as well as through sexual intercourse.
The minimum vaccination target set by PHE for local areas is 80%, but local teams are encouraged to aim for 90% or above.
England has seen declining rates of HPV vaccination over recent years, falling from 86.7% in 2013-14 – when girls were recommended to get both doses by the end of Year 8 – to 83.9% last year.
This was a slight improvement on 2017-18, when coverage was at 83.8%, but means almost 50,000 young girls were left unprotected.
Robert Music, chief executive of cervical cancer charity Jo's Trust, said it was positive that uptake remained high, but that there was much more work to do to close the gap between different parts of England.
Last year coverage for Year 9s ranged from a low of 56.7% in London's Waltham Forest to a high of 96.7% in Telford and Wrekin, in Shropshire.
Mr Music said: "[The HPV jab] is an extremely effective vaccine that will prevent many from going through a cervical cancer diagnosis, which will ultimately save lives.
"Yet we are faced with wide variation in uptake across England meaning many young women will not benefit.
"There is much targeted work to do to close the gap, and we must look at reaching communities where awareness and uptake is particularly low."
Dr Vanessa Saliba, from Public Health England, said: "The UK HPV immunisation programme is one of the most successful around the world, continuing to achieve high coverage with millions of doses of vaccine given to girls in the UK since its launch in 2008.
"We encourage parents of all eligible girls to ensure they take up the vaccine when it is offered.
“Girls who missed either dose of their HPV vaccine should speak to their school nurse or GP and arrange to get the vaccine as soon as possible as they remain eligible until their 25th birthday."
HPV vaccines were also rolled out to 12 and 13-year-old boys in September, which will help prevent future cases of cervical, mouth, throat and anus cancers, she added.