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National follow-up of rotavirus vaccination in Childhood Immunisation Programme

This project will monitor the rotavirus vaccination coverage, possible adverse events after immunisation and effects of the vaccination programme on disease incidence in the population.

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Vaccination coverage

All vaccines offered in the Childhood Immunisation Programme are registered in the Norwegian Immunisation Registry, SYSVAK. A vaccination date is registered for each given vaccine so that healthcare professionals can see when the next vaccine dose is due. Data from SYSVAK are also used to monitor diseases for which vaccination is used. The overview of who has been vaccinated or not is used to compare the incidence of rotavirus infection in the two groups and to study the effect of vaccination. Registration in SYSVAK also provides an overview of the vaccination coverage at county and national level.

Possible side effects (adverse events)

In Norway, adverse events after immunisation are monitored by the Norwegian Medicines Agency in collaboration with the Norwegian Institute of Public Health. Healthcare personnel are obliged to report unexpected or serious adverse events after immunisation. The Norwegian Institute of Public Health assesses the severity and causality of each reported event and uses these as a basis for advice on further vaccination. This information is forwarded to the European database for adverse drug reactions, to the World Health Organization's international drug safety database and to the vaccine producer's own databases. In this way, early detection of frequently reported side effects is possible.

During the first year of introduction of any new vaccine in the immunisation programme, an extended monitoring of all adverse events is used. The same monitoring was performed for rotavirus vaccine from October 2014 to October 2015. During this period health professionals were encouraged to report all adverse events, and not only those that are usually mandatory to report (such as serious or unexpected events). The Norwegian Institute of Public Health, in collaboration with the Norwegian Medicines Agency, publishes regular overviews of received reports online.

During vaccine trials, the rotavirus vaccine was found to be safe and not associated with any serious adverse events. Side effects such as diarrhoea, irritability, abdominal pain, flatulence (wind) and rashes could occur.

Rare adverse events such as intussusception may occur after rotavirus vaccination. Intussusception is a condition in young children, where part of the intestine twists into the intestinal section below, which may impede or block the blood supply to the twisted area. Studies that monitor safety after rotavirus vaccine introduction have observed that a small increased risk of intussusception cannot be excluded (1 - 5 additional cases per 100,000 vaccinated individuals). The association between rotavirus vaccination and intussusception is weaker if the vaccine is given within the recommended age limits, which is the reason for strict age limits for rotavirus vaccination applied in Norway.

There is an ongoing study to estimate the incidence of intussusception in Norwegian children prior to the introduction of the vaccine. This study will monitor whether there has been a change in the incidence since it was introduced.

Vaccine efficacy

1. Mandatory reporting and national reference function for rotavirus infection

The Norwegian Institute of Public Health monitors the disease incidence and the various rotavirus strains through the Norwegian Surveillance System for Communicable Diseases (MSIS) and the reference rotavirus laboratory.

2. Rotavirus hospital study

In order to be able to monitor vaccine effectiveness on severe rotavirus disease in more detail, a study of the rotavirus incidence in young children began in January 2014. The parents of children under 5 years who had been examined for diarrhoea and vomiting at five Norwegian hospitals were invited to participate.

How is the study conducted?

The Norwegian Institute of Public Health is responsible for the rotavirus study under the direction of NorEPIS (Norwegian Enhanced Paediatric Immunisation Surveillance Network), a research network for diseases that are preventable by vaccine. In NorEPIS, researchers from the Norwegian Institute of Public Health collaborate with health personnel in the paediatric and microbiological departments at five major Norwegian hospitals; Østfold Hospital Kalnes, St. Olavs Hospital in Trondheim, Stavanger University Hospital, Akershus University Hospital and Oslo University Hospital Ullevål.

The parents of all the participants in NorEPIS provide written consent and faecal samples are taken from the child. The samples are tested for possible viruses and bacteria as part of the standard hospital routines. In addition, each sample is sent to the laboratory at the Norwegian Institute of Public Health, for testing with more advanced methods for both rotavirus and other viruses. Positive samples are further tested to examine rotavirus strains. The available rotavirus vaccines specifically target the most common strains of rotavirus. However, once the rotavirus vaccine is introduced, other rotavirus types may begin to circulate in the population. Therefore, all virus strains are characterised and changes are monitored over time.

Information about the child’s health is collected via a questionnaire, including symptoms, severity of vomiting and diarrhoea, and other relevant information. Data from the study will be used to compare the incidence of rotavirus infection among those who are vaccinated against rotavirus and those who are not. The questionnaire can provide important information about the severity of the infection and can help to identify reasons for possible vaccine failure.

Links to other registries

Data from the study are linked to the Norwegian Immunisation Registry, SYSVAK and the Medical Birth Registry in order to better investigate the vaccine’s effectiveness.

Financing and approval

The study began in January 2014 and will continue until data about the sufficient data about vaccine’s effectiveness are collected. The study is funded by the Norwegian Institute of Public Health and has no affiliation with the pharmaceutical industry. The project is approved by the Regional Committee for Medical and Health Research Ethics.

3. Disease burden studies of rotavirus infection before and after vaccine introduction

Rotavirus vaccination primarily protects against severe rotavirus infection and, to a lesser degree, against milder disease. The primary objective of rotavirus vaccination is to reduce the incidence of severe rotavirus infection with dehydration leading to hospitalisation or death. Vaccination is also expected to reduce the incidence of moderate and mild rotavirus infection, which will result in fewer GP and out-of-hours primary care consultations. In some countries it has been shown that introducing rotavirus vaccines into the childhood immunisation programme can also protect unvaccinated older children and adults against rotavirus infection.

In order to monitor the incidence of gastrointestinal infections in Norway before the vaccine was introduced, registry-based studies were initiated for all patients with gastrointestinal infections who were admitted to hospitals or who had a primary care consultation. Data about patients with rotavirus infection and gastrointestinal infection with other causes are obtained from the Norwegian Patient Registry and the KUHR database for control and payment of healthcare reimbursements, and the Cause of Death Registry. A few years after introduction of the vaccine, data will be retrieved to investigate how the incidence has changed. These studies will examine the overall impact of rotavirus vaccination in the entire population, including those who are unvaccinated.

Data protection

Only de-identified data are available for researchers in all studies. Study participants cannot be identified when the results are published. 

Faecal samples taken as part of NorEPIS are stored in a biobank at the Norwegian Institute of Public Health and are analysed in de-identified form. Data from the questionnaires are stored in the same way without name or personal identification number. A code number associates the participant with their information through a coupling key. This key is stored securely and only a few authorised project staff have access to it. Data and samples are anonymised at the end of the project, so they cannot be associated with participants. The end of the project is currently set to 31.12.2024.

Publication of results

Results from the monitoring studies will be published in scientific journals and on the Norwegian Institute of Public Health's website.

Publications

  • Edwards HC, Bekkevold T, Flem E. Lost workdays and healthcare use before and after hospital visits due to rotavirus and other gastroenteritis among young children in Norway, Vaccine 2017, Jun 16;35(28):3528-3533.
  • Shin M, Salamanca BV, Kristiansen IS, and Flem E. Healthcare Costs of Rotavirus and Other Types of Gastroenteritis in Children in Norway. Pediatr Infect Dis J 2016 Apr;35(4):e97-e101.
  • Bruun T, Salamanca BV, Bekkevold T, Vainio K, Gibory M, Haugstad K, Rojahn A, Jakobsen K, Storvold G, Lunde A, Stordal K, Kanestrom A, Eidem MO, Døllner H, Skanke LH, Nordbø SA, Sivertsen HC, Gilje AM, Haarr E and Flem E. for the Norwegian Enhanced Pediatric Immunisation Surveillance (NorEPIS) Network. Burden of Rotavirus Disease in Norway: Using National Registries for Public Health Research. Pediatr Infect Dis J. 2016 Apr;35(4):396-400. 

Presentations

  • Flem E. Rotavirus vaccination in Norway: status and early impact. 5th European Expert Meeting on Rotavirus Vaccination. Utrecht, The Netherlands, 20-22 March, 2017.
  • Bruun T, White R, Flem E. Intussusception among Children in Norway: What to Expect After Rotavirus Vaccine Introduction? 5th European Expert Meeting on Rotavirus Vaccination. Utrecht, The Netherlands, 20-22 March, 2017 (poster).
  • Edwards Hansen C, Flem E, Freiesleben De Blasio B, Valcarcel Salamanca B. Is Ongoing Rotavirus Vaccination in Norway Cost-Effective? 16th Biennial Society for Medical Decision Making European Conference, London, UK, June 12-14, 2016.
  • Bruun T, Salamanca BV, Flem E. Epidemiology of Intussusception and Kawasaki Disease among Children in Norway: Assisting Safety Monitoring of Rotavirus Vaccine. European Academy of Paediatrics Congress. Oslo, Norway, 20 September, 2015.
  • Bruun T. Rotavirus disease revisited:  snapshot prior to vaccine introduction in Norway. 4th European Expert Meeting on Rotavirus Vaccination. Santiago de Compostela, Spain, 23-25 March, 2015.
  • Bruun T. Preparing for rotavirus vaccine introduction in Norway - how to monitor disease burden and vaccine impact? European Scientific Conference on Applied Infectious Disease Epidemiology, Stockholm, Sweden, 5 November, 2014.

Rotavirus vaccine

The rotavirus vaccine has been offered to all children born after 1st September 2014 through the Childhood Immunisation Programme in Norway. The first vaccine dose is given when the child is 6 weeks old and not later than 12 weeks. The second dose is given at 3 months of age and at the latest by 16 weeks of age. The minimum interval between doses is 4 weeks.