National surveillance of HPV vaccination programme
When the vaccine against human papillomavirus (HPV) was introduced in 2009/2010, a surveillance programme was established to monitor its efficacy, unwanted effects and vaccination coverage.
The surveillance programme includes several research projects that will study the effect of the immunisation programme on the incidence of HPV infection, cervical dysplasia (pre-cancerous cellular changes in the cervix) and cervical cancer.
The HPV vaccine has been offered to girls in the 7th grade as part of the Childhood Immunisation Programme since the 2009/2010 school year. Since November 1st 2016, the vaccine is being offered to women born in 1991 or later through a two-year catch-up programme. The vaccine protects against the HPV-types that most frequently cause cervical cancer.
When a vaccine is introduced in the Childhood Immunisation Programme, it is important to follow up the effect of the vaccine on the incidence of the diseases in the population. The effect of the HPV vaccine can be measured by studying the changes in the incidence of cervical dysplasia and cervical cancer. It can take a long time from infection with HPV until cervical dysplasia or cervical cancer are discovered so surveillance of the HPV vaccine will continue over many years.
What is being monitored?
1. Vaccination Coverage
In Norway, all vaccinations in the Childhood Immunisation Programme are recorded in the national immunisation registry, SYSVAK. Information about which vaccines are given, how many doses and when they are given is recorded for each individual. Information about vaccines given and immunisation certificates are available from the online My Vaccines (helsenorge.no).
This information is available for health professionals. Data from SYSVAK are used to monitor the efficacy of vaccination on the diseases in the programme. It is necessary to know who has been vaccinated and who has not when comparing the incidence and development of HPV infection among the two groups. Registration in SYSVAK also provides an overview of the vaccine coverage for the different vaccines at municipal, county and national levels.
2. Side effects
All vaccines in the Childhood Immunisation Programme are carefully monitored to identify any unwanted effects. Serious and / or unexpected events are reported to the Norwegian Institute of Public Health and are reviewed in collaboration with the Norwegian Medicines Agency. Norway also participates in a European collaboration for surveillance of unwanted effects after vaccination and reports any unwanted and suspected side effects in Norway to the European network.
3. Vaccine efficacy
The incidence of diseases covered by the immunisation programme is routinely monitored in order to measure vaccine efficacy in the population. Cases are reported by doctors and / or laboratories to the Norwegian Surveillance System for Communicable Diseases (MSIS) and are compared with vaccination information from SYSVAK. In addition, the effects are monitored through research projects.
HPV vaccine efficacy can be measured by studying changes in the incidence of HPV infection, cervical dysplasia and cervical cancer. In addition, changes in the incidence of the different HPV types are studied to see if the types that the vaccine will protect against are becoming rarer among vaccinated women. The efficacy of the vaccine against other HPV types is also being studied to monitor cross-protection.
The prevalence of HPV infection among non-vaccinated and vaccinated young women in Norway are being studied by testing urine samples for HPV from different cohorts aged 17 to 21 years in several national studies. By February 2017, more than 30,000 young women had participated. The results show that the prevalence of HPV among unvaccinated 17-year-olds is high and HPV is detected among 15-20 per cent of the girls. The incidence is even higher among 21-year-olds and about 45 per cent test positive for HPV in urine samples (1). This shows that HPV infection is very common among young women. The HPV types included in the current vaccine are commonly encountered.
Preliminary analyses of HPV incidence in vaccinated cohorts show a definite reduction in vaccine-related HPV types compared to unvaccinated cohorts. These analyses are ongoing.
Cervical dysplasia and cervical cancer are routinely reported to the Cancer Registry of Norway (2).
By compiling data from the Cancer Registry and SYSVAK, the incidence of cervical dysplasia and cervical cancer among vaccinated and unvaccinated women can be compared.
In addition, the Cancer Registry reports all cervical dysplasia and cervical cancer cases to MSIS (3). For a sample of women with cervical dysplasia and all cases of cervical cancer, tissue samples are obtained from the country's pathology laboratories for HPV analysis by the HPV reference laboratory at Akershus University Hospital.
Positive HPV tests are registered in MSIS. By compiling the test results from MSIS and vaccination information from SYSVAK, the effect of the HPV vaccine on incidence and changes of HPV strains in cervical dysplasia and cervical cancer can be monitored.
The HPV study of tissue samples from women with cervical dysplasia or cervical cancer is authorised by the MSIS regulations. Women can request that their unused samples should not be stored after HPV-testing (4).
1) Molden T, Feiring B, Ambur OH, Christiansen IK, Hansen M, Laake I, Meisal R, Myrvang E, Jonassen CM, Trogstad L. Human papillomavirus prevalence and type distribution in urine samples from Norwegian women aged 17 and 21 years: A nationwide cross-sectional study of three non-vaccinated birth cohorts. Papillomavirus Research, May (2016).