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National surveillance of the HPV vaccination programme (project description) - project description

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When the vaccine against human papillomavirus (HPV) was introduced in the Childhood Immunisation Programme in 2009/2010, a surveillance programme was established to monitor its efficacy, unwanted effects and vaccination coverage. The programme includes continuous follow-up of vaccination coverage and side effects, as well as research projects that investigate the effects of the vaccination program on the occurrence of HPV infections, precursors to cervical cancer and later cervical cancer.


Summary

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. Since autumn 2018 boys have also been offered HPV vaccine as part of the Immunisation Programme.

When a vaccine is introduced in the Childhood Immunisation Programme, it is important to follow vaccination coverage, the safety of the vaccine and its effect on the incidence of the diseases in the population. The effect of the HPV vaccine among women can be measured by studying the changes in the incidence of cervical dysplasia and cervical cancer. However, this can only be done some time in the future because can take a long time from infection with HPV until cervical dysplasia or cervical cancer are discovered.  Similarly, the vaccine's effect among men will be measured by studying the changes in HPV-related cancers among men over time. 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 and through the HPV vaccine catch-up programme are recorded in the Norwegian 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 Vaccines service (provided by helsenorge.no).

This information is available for health professionals. Data from SYSVAK are used to monitor the effect 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 county and national levels.

2. Side effects

All vaccines in the Childhood Immunisation Programme are carefully monitored to identify any possible side effects. Serious and / or unexpected events, as well as suspected side effects after vaccination 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. In addition, studies are being done to investigate whether there is a possible association between HPV vaccination and possible side effects. In 2017, a study from the surveillance programme showed that girls who had one or more doses of the HPV vaccine did not have a greater risk of developing chronic fatigue syndrome (CFS/ME) than girls who had not taken the vaccine (1).

3. Vaccine efficacy

Vaccine efficacy among girls

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 and 21 years in several national studies. By December 2018, about 45,000 young women have participated. The results show that the prevalence of HPV among 17-year-olds that have not been offered HPV-vaccine is high and HPV is detected among 15-20 per cent of the young women. The incidence is even higher among 21-year-olds and about 45 per cent test positive for HPV in urine samples (2). This shows that HPV infection is very common among young women. The HPV types included in the current vaccine are commonly encountered.

A study from the surveillance programme showed that the first cohort to be offered the HPV vaccine in 7th grade (born in 1997) had a lower incidence of HPV than girls in the older age groups who were not offered the vaccine. For the 1997-cohort as a whole, the incidence of all HPV types combined was reduced by 42 per cent, whereas the incidence of the types that the vaccine protects against was reduced by 81 per cent (3).

Cervical dysplasia and cervical cancer are routinely reported to the Cancer Registry of Norway (4). 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 (5). 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 (6).

Vaccine efficacy among boys

From autumn 2018, boys have been offered the HPV vaccine as part of the Childhood Immunisation Programme. The effect of the HPV vaccine among men can be measured by studying the changes in incidence of HPV-related cancer among men over time.  However, this can only be done after many years because it can take years from when a boy/man is infected until cancer develops. In order to measure the effect of the vaccine on HPV infection among boys, young men will be invited to participate in repeated national studies, where urine samples from different cohorts will be tested for HPV, similar to the ongoing studies for women.  In autumn 2018, 10 000 young men (21 years) were invited to supply a urine sample. In 2019, 15 000 young men (17 years) will be invited to participate. The urinesamples will be tested for HPV to give a picture of HPV incidence among unvaccinated age groups. Later, studies among vaccinated men will contribute to knowledge about the effect of vaccination on HPV incidence. 

Referanselitteratur

1) Feiring B, Laake I, Bakken IJ, Greve-Isdahl M, Bruun Wyller V, Håberg S, Magnus P,
Trogstad L. HPV vaccination and risk of chronic fatigue
syndrome/myalgic encephalomyelitis: A nationwide register-based study from
Norway.
Vaccine 2017;35: 4203-4212.

2) 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).

3) Feiring B, Laake I, Christiansen IK, Hansen M, Stålcrantz J, Ambur OH, Magnus P, Jonassen CM, Trogstad L. Substantial decline in prevalence of vaccine-type and non-vaccine type HPV in vaccinated and unvaccinated girls 5 years after implementing HPV vaccine in Norway. Journal of Infectious Diseases 2018; 16. July 2018.

4)  Forskrift om innsamling og behandling av helseopplysninger i Kreftregisteret (Kreftregisterforskriften) §2-1 (Helsepersonells dokumentasjons- og meldeplikt) (Lovdata)

5) Forskrift om Meldingssystem for smittsomme sykdommer (MSIS-forskriften) §2-3 (Meldingsplikt for laboratorier) (Lovdata)

6) Forskrift om Meldingssystem for smittsomme sykdommer (MSIS-forskriften) § 1-8a (Biobank tilknyttet MSIS) (Lovdata)