Improved registration of vaccinations - but there’s still room for improvement

Statens Serum Institut (SSI) has studied the degree of under-reporting of the 5-year vaccination in the Danish Vaccination Register (DVR), and the causes of missing registration/vaccination with vaccine among children living in the Municipality of Copenhagen.

The Danish Health Authority recommends that children are vaccinated in accordance with the Danish childhood vaccination programme. The coverage of the programme is monitored via the Danish Vaccination Register. Coverage is generally high; however, it varies from one vaccine to the next, as well as geographically and according to social conditions. Coverage is high for the vaccines given early in life, whereas coverage for vaccinations given at 4-5 years of age is lower. Copenhagen is among the municipalities with the lowest coverage, and the 5-year vaccination (booster vaccination against diphtheria, tetanus, whooping cough and polio) is among the vaccines with the lowest coverage (89%) according to the DVR. Earlier studies have shown that part of the low coverage is due to missing registration of vaccinations in the DVR, even though the children have, in fact, been vaccinated.

The SSI has studied the degree of missing registration of the 5-year vaccination in the DVR and calculated an adjusted vaccination coverage. Parents to children born in 2010 and living in Copenhagen who had not been registered as having received the 5-year booster were asked to participate in a questionnaire study to establish factors of importance to missing vaccination.
We estimated that the vaccination coverage for the 5-year vaccination could be adjusted with 2 percentage point, whereas the vaccines given earlier in the child’s life could be adjusted less. A similar study from 2013 found that the coverage could be adjusted by 3-4 percentage points.

“The findings seem to indicate that the doctors are now reporting the vaccinations more accurately in the DVR than in earlier studies, and that may, among others, be explained by the fact that since 2014 Statens Serum Institut has sent out reminder letters in case of missing registration/vaccination in the DVR,” notes Palle Valentiner-Branth, Section Head SSI.

Among the children who had not been vaccinated, the most frequently stated causes were forgetfulness (31%), that the parents had opted out of having their child vaccinated (26%) and that the family had moved to Denmark from another country and had not been aware of the Danish vaccination programme (17%).

“The study also showed that some social and family-related factors contribute to determining if a child has been registered with a 5-year booster in the DVR”, explains Palle Valentiner-Branth, Section Head SSI, “We established that children from large families, children who live with one parent only or where the parents do not have joint custody and children to parents from other countries than Denmark had more frequently not been registered as having received the vaccine.”

“A large part of the explanation why children to parents from other countries than Denmark carried a higher risk of not having been registered is likely that the child has been vaccinated abroad and therefore the vaccination had not been registered in the DVR,” notes Palle Valentiner-Branth.

For more information about the study, please see EPI-NEWS 20/19.