If one abstains from sexual intercourse the probability of contracting HPV viruses is very slight or even zero. People without a sexually active history are in principle “naive” vis-à-vis HPV viruses.
In this context “naive” indicates that the immune system has not come into contact with the HPV viruses and has not developed a specific defense response.
Preventing infection by a Papilloma virus, (apart from abstinence) therefore requires a vaccination. The vaccination process is all the more efficient when given to “naive” subjects (they have not been in contact with the Papilloma viruses). Thus early vaccination of young girls who have not yet had sexual intercourse has the advantage of beating the virus before it has had a chance to infect.
In France this is how the HPV vaccination is recommended:
The first target group for the Papillomavirus vaccine includes all girls aged 9 to 14 and the next target group is all young women under 19
This policy is to target the vaccination where it has most efficacy; those who have not yet been in contact with any strain of the virus.
The vaccine stimulates the production of antibodies which prevents the virus entering the cells around the genitalia. However, once the virus is established the antibodies cannot prevent its development, hence the advantage of vaccinating the “naive” population cohorts.
These vaccines do not work with all Papilloma viruses:
The bivalent Cervarix vaccine (GSK laboratories) targets HPV 16 & 18.
The quadrivalent Gardasil® vaccine (MSD Sanofi-Pasteur laboratories) targets HPV 6, 11, 16 & 18.
When we remember that HPV 16 & 18 are responsible for between 70-80% of cervical cancer cases in France and throughout the world, then vaccination cannot protect against all types of cancerand therefore screening must continue includingmonitoring ofthe vaccinated population.