No 10 - 2024

Vaccination coverage in Denmark; results from recent reports on influenza, COVID, and pneumococcal vaccination

Summary

Statens Serum Institut continuously conduct surveillance of infectious diseases and vaccination coverage in Denmark. As part of this surveillance, the vaccination coverage for the influenza-, COVID-, and pneumococcal vaccination programme have been described in four reports for the 2022/23 season. These reports aim to explore determinants (factors) of importance for the vaccination coverage and to identify groups in which vaccination coverage is low.
The four reports are available here (in Danish language)

Influenza vaccination in children

In the 2022/23 season, an influenza vaccination programme was available for children aged 2-6 years. The purpose of this vaccination offer was to reduce the overall influenza disease burden in the society and protect the Danish healthcare against a double epidemic of influenza and COVID-19. Vaccination of children was offered as a nasal spray with live attenuated influenza virus. The vaccination coverage was low (22%) in 2022/23, and slightly lower among children 4-6 years than among children 2-3 years. The vaccination coverage in the 2022/23 season was lower than the previous season (32% in 2021/22). The vaccination coverage was similar among children of Danish and non-Danish origin, (22% vs 26%), though considerable differences were observed according to the children’s country of birth. Children born in Bulgaria, Lithuania, the Ukraine, Poland and Rumania, the Faroe Islands and in Island had a particularly low coverage (7-15%), whereas children born in India had the highest vaccination coverage (55%). The vaccination coverage was affected by geographical residence. Children residing in rural municipalities had the lowest coverage (11-12%), whereas children residing in a number of municipalities in North Zealand and close to the larger cities had the highest coverage (29-30%). Generally, children with chronic diseases had a higher vaccination coverage than children not affected by chronic diseases.

Influenza, COVID, and pneumococcal vaccination in adults

There has been an influenza vaccination programme to adults for a number of years in Denmark. The coverage has increased considerably in recent years from approx. 50% before the COVID-19 pandemic to approx. 80% after the pandemic. In the 2022/23 season, influenza vaccination was offered to all persons aged 65 years or more, to pregnant woman in their 2nd or 3rd trimester, to persons below 65 years of age who were at risk of serious disease, to healthcare and nursing staff and, as described above, to children aged 2-6 years of age.

Various COVID-19 vaccination programmes have been implemented since the roll-out of the initial COVID-19 vaccination programme in late 2020. In 2022/23, COVID-19 vaccination was offered to all persons aged 50 years or more, to pregnant women in their 2nd or 3rd trimester, to persons below 50 years of age who were at risk of serious disease and to healthcare and nursing staff.

Because of the COVID-19 pandemic, a free pneumococcal vaccination programme was introduced in April 2020 for persons aged 65 years or more and for persons below 65 years of age who were at increased risk of invasive pneumococcal disease, i.e. meningitis and sepsis. The vaccination programme aimed to reduce the number of persons with serious infections requiring treatment or hospital admissions, and to reduce the risk of overloading the Danish healthcare system during the COVID-19 pandemic. The report on pneumococcal vaccination is based on data from April 2020 to January 2023 corresponding to the entire period during which a pneumococcal vaccination offer has been in place. The influenza and COVID reports are based on data restricted to the 2022/23 season.

The results from the three reports shows an overall high vaccination coverage among persons aged 65 years or more for the influenza, COVID-19, and pneumococcal vaccination programmes, with coverages of 81%, 86%, and 77%, respectively. However, the reports also reveal considerable variations in vaccination coverage across geography and country of origin. Persons with chronic diseases generally had a higher vaccination coverage than persons who were not affected by chronic diseases.

Generally, the vaccination coverage was slightly lower among the 65-74-year-olds than among people aged 75 years or more. Furthermore, the vaccination coverage was lower among persons of non-Danish origin and among persons who had not been vaccinated during previous seasons. These findings indicate that the vaccination programmes are largely followed by the same group of persons. Additionally, vaccination coverage varied geographically as areas west of Copenhagen, some rural municipalities and also some islands had a lower coverage. In addition, vaccination coverage also varied considerably by country of birth and persons born in the Ukraine, Rumania and Somalia had the lowest vaccination coverages (11-36%).

Surveillance of the vaccination coverage and future vaccination measures

The results from these reports identify groups with low vaccination coverage, including persons born in some specific countries (Eastern Europe, among others) and persons living in areas west of Copenhagen, in some rural municipalities and on some islands. The reports cannot identify the causes of lower vaccination coverage in these groups and areas. However, the results underline the importance of taking into account that we now have documentation that some groups are likely harder to reach with existing programme measures when planning future seasonal vaccination programmes. The findings of the reports may be used when planning future national and local vaccination programmes, by targeting measures towards groups that we now know are characterised by a lower vaccination coverage.

The importance of socioeconomic status was not explored in any of the four reports, but this should be done in future reports, particularly in areas where an intervention potential may exist.

(A.C. Nordholm, I.R. Moustsen-Helms, B. Søborg, Department of Infectious Disease Epidemiology and Prevention)
6 March 2024