How the Danish Vaccination Registry became a cornerstone of Denmark’s immunisation service

Gary Finnegan

Gary Finnegan

October 27th, 2023

Gary Finnegan

‘Danish lessons: The system empowers citizens, makes health systems more efficient, and offers insights on vaccine uptake, safety and effectiveness. Other countries could take a leaf out of Denmark’s book.’

In 2013, Denmark launched the Danish Vaccination Registry. In late 2015, it became mandatory for health professionals to record their patients’ vaccinations in the system. In the early years, this applied only to vaccines included in the national immunisation programme. Today, all vaccines administered in Denmark, whether in a public or private setting, are registered ‒ including, for example, travel vaccines.

Read to learn about

  • The value of Immunisation Information Systems (IIS)
  • How Denmark uses data-driven insights
  • How it was set up and how it is kept up to date
  • Future potential uses for IIS in Denmark and beyond

The result is a comprehensive secure database that is of practical value to individuals and serves as a significant public health resource.

For the public, the system replaced physical vaccination cards and helped families to keep track of immunisation records. This ensures people can stay up to date with recommended vaccines, but also avoid duplication: if a parent is unsure whether their child had a second MMR vaccine, for example, they can consult their record.

GPs, who administer most vaccines in Denmark, can see which vaccines a patient has had and which ones might be due. Medical staff in hospital emergency rooms can consult the register too, saving time and resources. For example, if a patient presents with a wound, the register will instantly show when that patient last received a tetanus shot.

Doctor in uniform reading medical paper having appointment with one of patients in clinics

Among the challenges of setting up a system of this kind is encouraging health professionals to input the data and ensuring that various IT systems ‘talk’ to one another. Denmark addressed this by designing a system which is easy for GPs to use. When they update their patient’s record to include a new vaccine that they have administered ‒ a routine step required for payment ‒ the Vaccination Register is updated automatically.

Denmark: ‘an epidemiologist’s dream’

Denmark has a sophisticated system built around a 10-digit personal identification number, known as the CPR. It also has a number of world-class patient registries and a population which, by and large, is accustomed to data-driven public services.

‘We have a lot of registries linked to CPR data ‒ it’s an epidemiologist’s dream,’ said Dr Palle Valentiner-Branth, Head of Department, Department of Infectious Disease Epidemiology & Prevention at the Statens Serum Institut (SSI). ‘By linking data, it is possible to perform advanced studies on vaccines and vaccination behaviour.’

A doctor typing on a laptop with stethoscope on the table

One of the initial drivers for establishing a modern Vaccination Registry was a desire to follow the long-term impact of vaccination against human papillomavirus (HPV) which can cause cervical cancer. The Registry has also been used to pinpoint low rates of vaccine uptake in particular areas or communities which can help to design tailored campaigns if needed.

For example, researchers have looked at coverage of the second dose of MMR vaccine and linked it to data on schools. This work highlighted lower uptake in some Waldorf/Steiner schools, presenting opportunities to reach out to that community. While experts are not routinely trawling the database looking for trends, it can be done if the need arises. Approved academics can also access the data for research purposes.

Another key benefit of IIS is the potential for collecting high-quality data on vaccine effectiveness and for detecting safety signals early. Denmark has conducted effectiveness studies on COVID-19 vaccines, as well as flu and pneumococcal vaccines. In the early stages of the COVID-19 vaccine rollout, Danish authorities were quick to spot a specific safety issue which was very rare but very serious. The issue related to one of the vaccines allowing authorities to update recommendations based on data.

‘We were able to act at a much higher speed than would have been possible without a register,’ said Valentiner-Branth.

Reminders drive up vaccination rates

Danish authorities have used written and email reminders, sent two weeks before vaccination is due, to encourage attendance for recommended vaccines. If vaccination is not recorded within 30 days, another reminder can be sent. Parents can opt out of the reminders if they wish (vaccines are not mandatory), but most parents respond positively.

‘In surveys, the most common reason parents give for why their child is not vaccinated is that they forgot,’ explains Dr Valentiner-Branth. ‘Reminders are very effective. Personalised invitation letters also contribute to improved vaccination in older people.’

In fact, Denmark is the only European country to reach the target of vaccinating 75% of people aged 65 years and older against influenza in the 2020-2021 flu season. Just a few years earlier, the flu vaccination rate in this age group was 50%, but the Vaccination Registry enabled a proactive approach to engaging older people.

Line of Danish houses at the water side with boats in front

Flu vaccines are recommended every year, but pneumococcal vaccines are offered every six years in Denmark. Invitation letters were sent to people aged 65 years and older advising them of the opportunity to have vaccines against flu and pneumococcal disease. The following year, letters were sent based on the individual’s vaccination record. For example, a person aged over 65 who had their pneumococcal jab last year would receive a letter this year inviting them to have a flu vaccine only. ‘In this way, we can use the Registry to tailor invitations to the individual,’ Dr Valentiner-Branth told Vaccines Today.

In future, tailored campaigns focused on high-need or at-risk groups could be developed. These groups potentially include pregnant women, those who have had their spleen removed, or people with chronic conditions known to make people vulnerable to complications if infected with, for example, influenza.

In the meantime, the Danish Vaccination Registry stands as an example of what is possible when health authorities, health professionals and citizens embrace a data-driven approach to public health.

Background & context

A 2017 survey and a 2018 Handbook on designing and implementing Immunisation Information Systems (IIS) were published by the ECDC. The picture at that time was mixed, with countries moving at different paces from a range of starting points. IIS have been developed in several European countries; some are piloting systems at a regional or national level; and others are at the earliest stages of developing such a system.

At EU level, the European Commission’s Roadmap for strengthening cooperation against vaccine-preventable diseases (2019-2022), included plans to explore the development of a common vaccination ‘card’ which would be compatible with electronic IIS. The European Joint Action on Vaccination also explored this issue cross-border aspects of vaccination records, building on the work of and public-private collaborations (such as the IMI project, ADVANCE).

In the background, a much bigger initiative known as the European Health Data Space promises to make mobile digital health data a reality. It could have positive implications for IIS and, in particular, how this information links with other registries and individual records.

Progress on IIS up to 2020 was steady and incremental.

Then there was a global pandemic.

There was an urgent need to record COVID-19 vaccination in a way that was easy for people to use and compatible with a central European system. The COVID Digital Covid Certificate was widely used and sparked renewed interest in IIS.

Health authorities accelerating their work in this area can draw on the ECDC guidance as well as examples from peers, including Denmark.

What about Low- & Middle-Income Countries?

Many of the technical and operational challenges of electronic immunisation registries (EIR) have been surmounted in a number of low-middle-income countries (LMIC) which have significantly greater challenges to implementation than European countries.

In Rajasthan, an Indian state of nearly 80 million people, an EIR has been implemented by the NGO Khushi Baby so successfully that it is facilitating immunisation of thousands of zero-does children and has become the scaffold for a primary health care platform.

In another example, an innovative Smart Paper Technology is facilitating the capture of beneficiaries’ health data on paper by health workers, which is subsequently scanned and digitised, and is being used for national EIRs in Uganda and Gambia.